Dr. Layne Norton: The Science of Eating for Health, Fat Loss & Lean Muscle

ANDREW HUBERMAN: Welcome to
the Huberman Lab podcast, where we discuss science
and science-based tools for everyday life. I'm Andrew Huberman,
and I'm a professor of neurobiology
and ophthalmology at Stanford School of Medicine. Today, my guest is
Dr. Layne Norton. Dr. Norton is one of
the foremost experts in protein metabolism,
fat loss, and nutrition. He did his degrees in
biochemistry and nutritional sciences and is considered
one of the world experts in understanding how we
extract energy from our food and how exercise and what we
eat combine to impact things like body composition
and overall health. Today, we discuss an
enormous number of topics under the umbrella of
nutrition and fitness, including, for instance,
what is energy balance? That is, how do we actually
extract energy from our food? We also discuss the
somewhat controversial topic of artificial sweeteners,
whether or not they are safe or not
and whether or not they are an effective
tool for weight loss, in particular, for
people suffering from obesity and different
types of diabetes.

We also talk about gut health–
that is the gut microbiome– and how it's impacted
by food and how it can actually impact the
metabolism of the foods that we eat. We also discuss fasting, or
so-called intermittent fasting or time-restricted
feeding, what it does and what it does not do in
terms of how effective it is for weight loss and, perhaps,
even for health and longevity. We also talk about protein
and define very clearly how much protein each
and all of us need, depending on our daily
activities and life demands. We discuss the
various types of diets that you've probably
heard about, including ketogenic diets,
vegan diets, vegetarian diets, and pure carnivore diets, as
well as more typical omnivore diets, and how to
make sure that you get all of the
essential amino acids that are critical for healthy
weight maintenance, weight loss, or directed muscle gain. We also talk about supplements,
in particular, the supplements for which there is an immense
amount of science pointing to their safety and
efficacy for fitness and for overall
body composition.

What I'm sure will
become clear to you, as you hear Layne
talk about each and every one of
these topics, is that he has an incredible
ability to both understand the mechanistic science
but also the real world applications of the various
discoveries that are made in particular papers
and, in particular, in the randomized
controlled trials. That is when a given scientific
hypothesis has been raised. He's extremely good at
understanding why it was raised but also at evaluating
whether or not it works in the
real world, which is what I believe most everybody
out there is concerned with. I think this is one of
the things that really distinguishes him
from the other voices in the nutritional landscape. I assure you that by the
end of today's discussion, you will have a much clearer
understanding about what the science says about
nutrition, about fitness, and about how different diets
and fitness programs combine to achieve the
results that you want.

Before we begin, I'd
like to emphasize that this podcast is separate
from my teaching and research roles at Stanford. It is, however, part
of my desire and effort to bring zero cost to
consumer information about science and
science-related tools to the general public. In keeping with
that theme, I'd like to thank the sponsors
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And I should just
mention that the library of those supplements is
constantly expanding. Again, that's
livemomentous.com/huberman. And now, for my discussion
with Dr. Layne Norton. Layne, Dr. Norton, thank
you so much for being here. This is a long time coming. And I have to say, I'm really
excited because I've seen you in the social media sphere. I've also listened to a
number of your other podcasts. And as a fellow PhD scientist,
I feel a great kinship with you. I know you have
tremendous experience in fitness and nutrition,
a number of areas. We also got a lot of
questions from our audience. And I'm really looking forward
to talking with you today. LAYNE NORTON: Yeah,
I'm excited, too. I mean, like you said,
it's been something we've been talking
about for a long time. So I was glad we were
able to make it happen. ANDREW HUBERMAN: Yeah, indeed.

And I think some
of the audience has requested a debate or a battle. And I can tell you right now,
it's not going to happen. Actually, one of the things that
brought Layne and I together, in conversation online and
then via text, et cetera, was the fact that I
love to be corrected, and that's what happened. I did a post about
artificial sweeteners, which we will talk about a little
bit later in the episode, and Layne pointed out some areas
of the study that I had missed or, maybe, even misunderstood.

And I revised my opinions
and I think it's wonderful. And other studies have
come out since then. So hopefully, our
conversation will serve as a message of how
science and actionable science can be perceived and
that it doesn't always have to be a battle. But hey, if we get into
it, we get into it. It won't get physical because
we know you would win. So in any case, I'd like
to start with something that's rather basic and
yet can be pretty complex, and that's this issue of energy
balance and energy utilization.

I think most people
have heard of a calorie. I am assuming that most
people don't actually know what that is in
terms of how it works, what it represents. And so maybe you
could just explain for people what happens when
we eat food, of any kind, and how is that
actually converted into energy, as a way of framing
up the discussion around weight loss, weight maintenance, weight
gain, and body composition. LAYNE NORTON: So it's
a great question. And like you said, this is one
of those things where people use the term calories
in, calories out, and they say, well,
that's way too simplistic. I'm like, if you look at what
actually makes up calories in, calories out, it's
actually very complicated. So let's deal with what
you mentioned first. What is the calorie? Because I think a lot of people
don't quite understand this. So a calorie just refers to
a unit of energy, of heat specifically. And so what does that
have to do with food? What does that have to do
with what we digest and eat? Really, what you're
talking about is the potential
chemical energy that is in the bonds of the
macronutrients of food.

And by digesting,
assimilating, and metabolizing those nutrients, we
are able to create energy and the in-product
of that, mostly, is ATP, adenosine triphosphate,
which is your body's energy currency. So to understand ATP,
just try to think about– if you're trying to power
these various reactions in your body– and we're talking
about tens of thousands of enzymes that require ATP– it doesn't make
sense that you would have to create a bunch
of micro explosions.

You want something that can
transfer high-energy phosphates to power these
reactions, to give up essentially its energy
to power something that might otherwise
be unfavorable. So a lot of metabolism
is simply creating ATP, which the end
of the line of that– I'm going to work
backwards– is what's called oxidative respiration. So that happens in
the mitochondria. Everybody's heard mitochondria,
a powerhouse of the cell. And that is done through
essentially creating a hydrogen ion gradient across
the mitochondria, which powers the production
of ATP by converting free phosphate plus ATP to ADP. Now the way that hydrogen
ion gradient is created is through creating hydrogen
ions that can be donated through the Krebs cycle.

Now the Krebs cycle is
linked to glycolysis. So if we talk about
carbohydrate metabolism, carbohydrates basically,
other than fructose, get converted into glucose,
which can go into glycolysis, and you can produce some
ATPs through glycolysis. And then it boils
down to pyruvate, then acetyl-CoA, which
goes to the Krebs cycle, produces a lot more
ATPs from that. If you talk about
protein, protein is a little bit different
because protein gets converted to amino acids,
which can be used for muscle protein
synthesis or protein synthesis in other tissues. But it also can be converted
through gluconeogenesis to glucose. And there also are some
ketogenic amino acids as well. And so you can have
a few different ways to get to the Krebs cycle.

Either being through
acetyl-CoA or through glucose going through the
glycolysis to pyruvate. Then you have fatty acids,
which are able to create energy through what's called beta
oxidation where, essentially, you're taking these fatty
acids and you're lopping them off two carbons at a time
to produce acetyl-CoA which, again, can go into
the Krebs cycle, produce those hydrogen
ions that can then power the production of ATP. So that's kind of like
at the cellular level of how this stuff works. But stepping back and
taking it back out, what does that have to do with
weight loss or weight gain? Well, when you think about
the balance of energy in versus energy out.

Sounds very simple. But let's look at
what actually makes up energy in versus energy out. First of all, you've
got to realize that the energy
inside of the equation is more difficult to
track than people think. So one, food labels,
which we like to think as being
from upon high, can have up to a
20% error in them. ANDREW HUBERMAN: Really? LAYNE NORTON: Oh, yeah. ANDREW HUBERMAN:
So a 100 calorie– something listed as 100
calories per serving, it could– what's actually
in there could be 80 or 120. LAYNE NORTON: Right. Exactly. So that's one aspect of it. The second aspect is there's
what's called your energy, but then there's also
metabolizable energy. So if you have food stuff with
say, a lot of insoluble fiber, typically, insoluble fiber
is not really digestible, and so you could have "quite
a bit of carbohydrate," know but if you can't extract
the energy from it– and typically, this is
because insoluble fiber from plant material, the
carbohydrate and even some of the protein is bound up
in the plant structure, which makes it inaccessible
to digestive enzymes.

And so this is what adds bulk
to your stool and whatnot. But again, reduces the
metabolizable energy in there. And there's some
evidence that based on people's individual gut
microbiome, that some people may actually be better at
extracting energy out of fiber compared to other people. So just starting
off right there, OK, there's quite a bit of play
in the energy inside of things. Now, one of the
things people will say is, well, see that's
why you shouldn't worry about tracking calories, because
the food levels can be 20% off. And what I'll say is, OK. I understand where
you're coming from. But typically, if it's off, it's
going to be consistently off.

And if you're consistent
with how you track it, eventually, you'll be able to
know what you're taking in. And that's like saying, well,
don't worry about tracking if you're– I like to use
financial examples. We know that to
save money, you have to earn more money
than you spend. Well, you can't exactly
know how much money you're earning at a time
because there's inflation and then there is– if you have investments, those
can be different interest rates and whatnot. It's like, OK, if
you have a budget, you have a reasonable idea
of what it's going to be. And you make
certain assumptions, but you can relatively guess. ANDREW HUBERMAN: Yeah. That's a good example. LAYNE NORTON: Right. So now, let's look
at the energy outside of the equation, which is
actually way more complicated. And so your energy out is
a few different buckets. The first one and
the biggest one is your resting metabolic rate. So your RMR. And that, for most people,
is anywhere from 50% to 70% of your total daily
energy expenditure.

Now, people use the term
metabolic rate and energy expenditure interchangeably,
but they're not the same thing. So your total daily
energy expenditure is the summation of all the
energy you expend in a day. ANDREW HUBERMAN:
Walking upstairs, exercise if you do it– LAYNE NORTON: Fidgeting. ANDREW HUBERMAN: Yeah. Plus your resting
metabolic rate. LAYNE NORTON: Right. So resting metabolic rate
is a big part of that, but it's not the only thing. So that's usually
about 50% to 70%. And sedentary people will be
on the higher end of that. So it'll be a bigger
proportion whereas people who are more active, it'll
be a little bit lower, not because their metabolic
rate is lower, but because they're
expending a greater percentage of their calories
from physical activity. Then you have something
called the thermic effect of food, which is a
relatively small percentage of your total daily
energy expenditure.

It's about 5% to 10%. And very difficult to
measure and usually what researchers do when
they're looking at this stuff is they just make an
assumption about it. They use a constant. But that's about 5% to 10% of
your daily energy expenditure. And that refers to
the amount of energy it takes to extract
the energy out of food. So think about your
body like a car. You don't just have
gas in your tank and it spontaneously starts up. You have to have a battery
so you put in energy so you can get the energy
out of the petrol that you have in your car. Similar with food, you
can't just eat food and then it just
appears in your cells and you start doing stuff. It has to be
systematically broken down and put into forms that
can actually produce energy.

And so you have to put some
energy in to achieve that. And a lot of times,
people will say something like, well, not all
calories are created equal. That's not true, because calorie
is just a unit of measurement. That would be like saying
not all seconds on a clock are created equal. Yes, they are. All sources of calories may have
differential effects on energy expenditure and appetite. So if we look at something
like fat, for example, the TEF of fat is
about 0% to 3%. Meaning, if you eat
100 calories from fat, your net will be
about 97 to 100. ANDREW HUBERMAN: So the
process of breaking down that fat, essentially,
subtracts some of the calories away because you used
it in creating energy– LAYNE NORTON: Correct.

ANDREW HUBERMAN: –by
breaking those chemical bonds to create ATP. LAYNE NORTON: Correct. Correct. So you have like, for example,
some enzymes that require ATP to run these processes. Now, fat is actually the easiest
thing to convert into energy. Then you have
carbohydrate, which has a TEF of like 5% to 10%. So you eat 100 calories
from carbohydrate. And obviously, the fiber content
makes a big difference on this. But if you eat 100
calories, you'll net 92 95. Protein is about
a 20% to 30% TEF. So if you eat
calories from protein, you're only netting 70 to 80. Now, you're still net– people say, well, you
can't eat too much protein. Well, people will ask, well,
can protein be stored as fat? The carbon's from
protein it's unlikely, it's going to wind
up in adipose tissue. But if you're eating
a lot of protein, overall as part of a lot of
calories, it has to be oxidized and it can't provide a calorie
cushion for other things to be stored in fat.

But protein itself does provide
a net positive for calories, but less so than
carbohydrate or fat. And tends to be more satiating. So again, when people talk about
are all calories created equal, yes, but all sources
of calories may have differential effects
on energy expenditure and appetite. So that's the TEF bucket
and the BMR bucket. Then we go to physical activity. And physical activity is,
essentially, two parts. There's exercise, which is kind
of your purposeful movements like you go out for a walk,
you do a training session. I mean, whatever. Any purposeful activity. And then you have
what's called NEAT which is non-exercise activity
thermogenesis, which I think is actually really cool. ANDREW HUBERMAN:
It's fascinating.

LAYNE NORTON: Yeah. It is. So I was actually hanging
out with somebody last night and I was noticing them,
they were fidgeting their feet and their fingers. And I said, have you
always been pretty lean? And they were like,
yeah, I never really had a problem
maintaining leanness. And when you look at the
obese resistant phenotype, people think they
have high BMR or they exercise a lot and really
what it seems to be as neat. They tend to– if they
overeat, they just spontaneously increase
their physical activity. Now, people get NEAT confused. I've heard people say,
well, I'm going to go out for a walk to get my NEAT up. That's not NEAT. NEAT is not something you
can consciously modify. What you're doing there, if
it's purposeful, it's exercise. So for example,
when I'm talking, if I'm waving around my
hands, if I'm tapping my feet, if I'm– whatever. That's NEAT. But trying to get yourself– I'm just going to
tap my foot more, well, now if I'm
consciously having to do this, then my focus– I mean, you know
how the brain works.

Very hard to do– you don't really do
two things at once. ANDREW HUBERMAN: Right. LAYNE NORTON: You switch
quickly between tasks, right? ANDREW HUBERMAN: Absolutely. Can I quickly ask, was the
person that you were referring to our friend Ben Bruno? LAYNE NORTON: No, no. But he is fidgety too. ANDREW HUBERMAN: Yeah. Amazing online fitness channel. He's a freakishly
strong individual. LAYNE NORTON: Yeah. ANDREW HUBERMAN: Yeah. And I can't remember
whether or not, Ben, you're a fidgetter or not. But anyway, I'll
have to go check and we'll measure
your fidgeting.

About non-exercise induced
thermogenesis NEAT, my understanding of the old
papers on this, old being, I guess, back to
the mid '90s, is that the calorie burn from NEAT
is actually pretty significant. We're not talking about 100
calories or 200 calories per day. We're talking about,
in some cases, hundreds of thousand– excuse
me, hundreds to maybe even close to 1,000 calories per day. Could you elaborate on that? LAYNE NORTON: Yeah. So there was actually a really
classic study, I think, from– I want to say it's
from Levine in 1995. It was metabolic ward study. And hopefully, I don't
butcher the study because I'm trying to
pull it out of my brain. ANDREW HUBERMAN: I don't expect
you to have that in your head. Although, I must say, you have
a quite extensive PubMed ID, grab bag in there. So– LAYNE NORTON: I try
to bring the receipts. I try to bring the receipts. ANDREW HUBERMAN: We will put a
link to this study in the show note captions. So people can peruse it
if they like it, yeah. LAYNE NORTON: So I believe
they had people overeat.

And I think it was by
like 1,000 calories a day and I think for six weeks. And I mean, this is
the metabolic ward. So this is very
tightly controlled. It's as tight as you get. And what was interesting
is, of course, on average, people gained weight
and gained fat mass. But some people gained
more than expected, and there was one person, in
particular, who only gained like just over 1/2 a kilo. They should have gained like– I think it was something
like 3 to 4 kilos.

It was predicted. And what they found
is this individual just spontaneously increased
their physical activity. He didn't purposefully
do it, it just happened. And I mean,
anecdotally, I've seen people who are, again,
very lean even eat a meal, sit down, and start sweating. And be very fidgety. There was a natural
bodybuilder back in the day named Jim Cordova. And this guy was just
very lean all the time, and he was exactly
that phenotype.

He would walk up
a flight of stairs and all of a sudden
he's sweating. Sit down eat a
meal, he's sweating. He's just– ANDREW HUBERMAN: He's a furnace. LAYNE NORTON: Just
expending energy. And what's very
interesting about NEAT is that seems to be
the most modifiable– I mean, exercise
is very modifiable because you can be
intentional with that. But of BMR, TEF,
and NEAT, NEAT seems to be far more modifiable. So even a bodyweight
reduction of 10%, they've observed
a decrease in NEAT of almost 500 calories a day for
a 10% reduction in body weight. Now, you also do
get a decline in BMR when you lose weight,
one, because you're just in a smaller body now and
so it takes less energy to lock them out. But also there's what's called
metabolic adaptation, which is a further reduction
in your BMR than expected from the loss of body mass.

And that's on average
usually around like 15%. But it does seem to be– there's new evidence coming
out on the metabolic adaptation from BMR. And it seems to
be a little bit– kind of in the
transition phases. So if you start a diet
within the first few weeks, you will have a reduction
in BMR that then just– thereafter, any
further reduction is mostly from the amount
of body mass you lose. And then if you, like for
example, finish a diet and move your calories
to maintenance, within a few weeks, BMR
starts to come back up. There is still a
small reduction, but I used to be
somebody who thought that BMR, metabolic
adaptation was a big reason why people stopped
losing weight or plateaued.

And now, I think it's
much more to do with NEAT. ANDREW HUBERMAN: Interesting. And you said that it
can't be conscious because that will distract
us from other activities. I don't know if you've had a
chance to look at this study. And I'll send it to you. Maybe I'd be fun to do a kind
of an online journal club about this at some point soon.

But there's a study that came
out of University of Houston recently having people do, now,
this is a long period of time. Four hours a day of, basically,
a soleus pushup, which is basically a heel raise. A seated catchphrase with
one foot not weighted. And then they
looked at it a bunch of things about glucose
metabolism and glucose clearance and insulin levels. And they didn't
conclude that people burned a ton of
calories, but what they concluded was that blood
sugar regulation improved greatly. And I think, there was
a lot of excitement about this at some
level, but based on everything you're telling
me, this fits perfectly with what's known about neat. So this fell somewhere
in between with– in between, excuse me,
sort of deliberate exercise and spontaneous movement. I guess they've tried to make
that spontaneous movement a little bit more conscious. LAYNE NORTON: Well,
what I'll tell people is if you're
worried about NEAT, one thing you can do,
like these watches, for example where people
are like, oh, well, told me I burned
these many calories.

They are not accurate
for energy expenditure. I mean, it is like, there
was a meta analysis in 2018, I want to say,
between a 28% and 93% overestimation of energy
expenditure by these watches. ANDREW HUBERMAN: Fitness track. So for those of you
listening, we're not going to name the brand. But fitness trackers– so
wrist-worn fitness trackers. LAYNE NORTON: And this
is across the board. ANDREW HUBERMAN: OK. LAYNE NORTON: So like
depending on the brand, it could be more or
less but, they all overestimated the amount of– the calories you
burn from exercise. So this is actually a great
example where people go, well, calories in, calories
out doesn't work for me, because I eat in a calorie
deficit, I didn't lose weight.

When I talk to
them, usually, they went to an online calculator. It's a few things. They went to an
online calculator, put in their information, it spat
out some calories to eat, and they ate that and
didn't lose weight. And it's like, well, what
do you think is more likely? That you're defying the laws
of conservation of energy or that you might
have not gotten the right number for you? ANDREW HUBERMAN: The
measurement tool was off.

LAYNE NORTON: Yeah. The next thing is a lot of
people weigh very sporadically. And I'll tell people
like, if you're going to make an intentional
weight loss a goal, and again, this can be
different for different people, but typically, I
tell people, weigh in, first thing in the
morning or after you go to the bathroom,
do it every day, and take the average
of that for the week. And then compare that to
the next week's average. ANDREW HUBERMAN: Can I ask
one– sorry to interrupt, but one quick question
about that when you say, go to the bathroom not
to get too detailed here unnecessarily, but are you
talking about urination and emptying your bowels? Ideally, because you did eat
a big meal the night before. LAYNE NORTON: Yeah.

ANDREW HUBERMAN: Yeah. Got it. LAYNE NORTON: Yeah. ANDREW HUBERMAN: So wake up,
use the bathroom in all forms that you're ready, and
then get on the scale, take that measurement, average
that across the week, and then maybe every Monday,
you take that value and see how it progresses. LAYNE NORTON: All right. And the reason I recommend
doing that is, if you're just sporadically weighing in, as
somebody who weighs themselves pretty regularly,
I mean, my weight will fluctuate 5, 6 pounds, and
not seemingly changing much. And that's just– those
short term changes are fluid. So I've had it before,
where week to week, my average didn't change. But between the lowest weigh
in from a previous week and the highest weigh in, might
have been like 8 pounds, right? So if you're somebody who
just randomly is weighing in and you're eating in
a calorie deficit, and you just weigh in
one day where you've just whatever reason holding some
more fluid, then you're oh, see, this isn't working when
in reality, your average might be dropping.

So that's one of the
reasons, and actually, believe it or not,
weight fluctuations are actually identified as a
major reason why people get discouraged from weight loss. It stops the buy-in, when
they have a fluctuation up. So that's one of the reasons– ANDREW HUBERMAN: Great point. LAYNE NORTON: –one
of the reasons early on that low carb diets
tend to work really well is because people
lose a lot of water weight really quickly, and
they get that buy-in. So they're, oh, this is working. ANDREW HUBERMAN: Yeah. We can return to
that in a little bit because I have theories
as to how that– when people eat
less carbohydrate, they excrete more
water, and they'll see– for the first time, they'll see
some definition in their abs, oh, my God, this diet's amazing. LAYNE NORTON: Yeah.

ANDREW HUBERMAN: And the fluid
loss does hold that promise. I think fluid loss can
do some other things. It might make people
literally feel lighter, although it can be– it
has some negative effects. I do have one quick
question, and I do want– we will return
to NEAT in a moment. But when you say,
the caloric burn as a consequence
of exercise, I want to ask about the caloric
burn during that exercise? So for instance, if
somebody is on the treadmill and they'll see, OK,
they burn 400 calories. Actually, I think
this is a month where a number of
prominent podcasters like Bert Kreischer, Tom
Segura, Joe Rogan, and others, I think they call
it "Sober October," but in addition to
avoiding alcohol, they're burning 500 calories
per day during the exercise.

LAYNE NORTON: Yeah. ANDREW HUBERMAN:
They're measuring it. A lot of people do this. They think– they take
track of weather– excuse me, take stock of how
many calories they burned. My understanding is that if
that particular form of exercise is a muscle building
form of exercise, that at some point later, there
might be an increase in muscle if you did everything
right, do everything right, and then you will
burn more energy as a consequence of
adding that tissue. That's a long process
as and we will discuss. But I have heard about this
post-exercise induced increase in oxidative metabolism. I'm probably not using the
right language in here. So if I were to go out, for
instance, and do some sprints. Run hard for a minute, jog for
a minute, run hard for a minute, and do that 10 times over. Let's assume I burn 400 calories
during that exercise bout. But my understanding is that
in the hours that follow, my basal metabolic rate
will have increased. Is that true, and is
it significant enough to care about? LAYNE NORTON: So answer
both of those questions.

Yes, there does seem
to be a small increase in metabolic rate,
and no, it does not appear to be enough to
actually make a difference. So when they look at– and again, this is
where I tell people– I think I have a good
perspective on this, because my undergraduate degree
was a biochemistry degree. So I was very into mechanisms. You know what I mean? It was like, oh, if we just do
this and this, we'll get this. And then I did nutrition
as a graduate degree, and then my advisor was so great
because you could do something over here and he could tell
you how it would affect vitamin D metabolism over here.

ANDREW HUBERMAN:
This is Don Lemon? LAYNE NORTON: Yeah, Don Lemon. So he would always
kind of say, yeah, but what's the outcome
going to be, right? So this is actually one of the
things I changed my mind on. Was I used to be
very much, well, I think high intensity interval
training is probably better because you get this
post-exercise energy burn which they do see in
some of these studies. But in the meta analyzes and
more tightly controlled studies where they equate work between
high intensity intervals and moderate or low intensity
cardio, so equating work, they don't see differences
in the loss of body fat. And so to me, if I'm
looking like, that's the example of a
mechanism, which is OK, we're seeing this small increase
in basal metabolic rate, that should lead to
increased loss of body fat. But again, remember, you're
capturing a snapshot in time. But we don't see a difference
in the loss of body fat. So what may be happening– and
again, I'm just speculating. But a way to explain it could
be, you might have an increase and then you might actually
have a decrease that tends to just wash it out, right? ANDREW HUBERMAN: I see.

And I have to imagine
some forms of exercise. This would be highly individual,
but will spike appetite more than others. So for instance, if I go out
for a 45-minute jog which I do. A 45 to 60-minute hike or
jog once a week, I just make it a point to do that or
ruck or something like that. Throw on a weight vest and hike. After that, I find I'm very
thirsty, I want to hydrate. But I'm not that hungry. And that's true of all
cardiovascular exercise for me.

But after I weight train,
about 60 to 90 minutes later, I want to eat the refrigerator. And so obviously,
calories in, calories out dictates that that will
play an important role as to whether or not I gain or
lose weight, et cetera. So is it safe to say that
the specific form of exercise that people choose needs to
be taken in consideration? Calories in, calories
out, so how much is burned during the exercise? Also how much that exercise
tends to stimulate appetite. I don't know whether
or not people explore this in their rigorous studies. And whether or not
that form of exercise actually increases lean
muscle mass or not. Now, we've taken
exercise and split it into a number of
different dimensions, but this is what you are
so masterful at is really parsing how the different
components work individually and together.

So if you would
just expand on that, I'd love to know
what you're thinking. LAYNE NORTON: Yeah. So this is actually a
really fascinating thing. So first thing, I
want to just go back to talking about like, for
example, Bert and Tom and Joe, we're going to do 500
calories a day on whatever. So those apparatuses
don't measure those things effectively either. Just like these watches. But the one thing I will
say is, if you are– like for example, if I do two
hours of resistance training, typically, this will say I
burned about 1,000 calories.

ANDREW HUBERMAN: That's a
lot of resistance training. LAYNE NORTON: Right. ANDREW HUBERMAN:
My weight workouts are warm up for 10 minutes and
then one hour of work done. LAYNE NORTON: I just– I love to train. ANDREW HUBERMAN: OK. And you can recover from. My recovery quotient
is pretty low. So I've been training
for 30 plus years, and I found that if I
do more than an hour of hard work in the gym,
meaning resistance training, 75 minutes maybe, I'm OK, but
past that, I have to take two, maybe even three days
off before I can train. My nervous system just
doesn't tolerate it well. So I limit it to
an hour, you know. LAYNE NORTON: And part of
that to remember is like, I've built up to that over
a long period of time. So you couldn't just throw
somebody in and start having them do two hours a day. It's not going to
go well for them.

ANDREW HUBERMAN: I'd like
to take a quick break, and acknowledge one of our
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athleticgreens.com/huberman to get the five free travel
packs and the year's supply of vitamin D3, K2. LAYNE NORTON: But I will say
about the calorie trackers, so if I'm used to– OK, I usually burn about 1,000
calories according to this, it's not accurate.

But if I go in tomorrow and I do
1,300, it may not be accurate– I don't know what
the exact number is, but I can be relatively
confident that it's more than the previous session. And so in terms
of comparison, it might be OK, like
within subject. And then the other thing I
was kind of circling around on was, if you're worried about
NEAT, tracking your steps can be helpful because people
step counts can spontaneously decrease when they're
on a fat loss diet, they don't even realize it. And that, again, not
a complete measure of NEAT, but what we've had
some clients do with our team building coaches is, they'll
say OK, you're, at 8,000 steps right now.

We're not going to add
any purposeful cardio. But whatever you need to do
to maintain that 8,000 steps, do that. And sometimes, they have to add
15, 20, 30 minutes of cardio, because they're spontaneous
activity that they're not even aware of goes down. ANDREW HUBERMAN: That's
a really excellent point. I've heard the 10,000
steps per day number was, we all heard that. And then I learned that, 10,000
were just kind of thrown out as an arbitrary number. So we're like get eight-hour
intermittent fasting thing, there's a story behind
that because actually I spoke to Satchin,
and it turns out that the graduate
student in his lab did that initial study, which
was on mice, by the way, was limited to being in
lab for about eight hours by their significant other. So the eight-hour feeding window
is actually the consequence of this person's relationship. So– LAYNE NORTON: That is
a really great point that people don't realize
when they– a lot of people will try to copy like
scientific studies. And I'll tell people like,
listen, scientific studies are so confined. You need to be very careful
with how broadly you apply what's in there.

Like they're a very big hammer
is the way I look at it. They're not a scalpel,
they're a big hammer. And I think, a lot of
times in terms of coaching, scientific studies will
tell you what not to do rather than what to do, right? But getting back
to your question about exercise,
appetite, so first off, I'm not really aware if
there's evidence showing like differential effects of
different forms of exercise on appetite, it's possible,
but again, it also could be like a
placebo effect, right? Because we– like for example,
you and I, grew up in an era where the muscle
magazines, it was like, well, as soon as you
finish your workout, you have your biggest
meal of the day. And when I say placebo
effect, I think people have the wrong idea of
what the placebo effect is. They think that's
just a feeling. Placebo effect can actually
change your physiology. People don't realize this. There's research showing
that a placebo or the power of suggestion is
basically as powerful as some pharmaceuticals. And one of the great examples
I like to use is– actually, there was a study we just
covered in our research review on creatine where
they did four groups– not supplemented with creatine,
told they weren't supplemented with creatine, not
supplemented, told they were supplemented,
supplemented, told they weren't,
supplemented, until they were.

Basically, it just matters
what they told them. ANDREW HUBERMAN: Really. LAYNE NORTON: Oh, yeah. ANDREW HUBERMAN:
This is incredible. I have to get this
study well so we can link to a colleague
of mine at Stanford. She's been on the podcast. I'd love to introduce
you to because I think you guys really riff. First of all, she was
a former D1 athlete and then as runs a lab at
Stanford in psychology. This is Alia Crum. And she's– and grew up in
this very athletic, obviously, and very, very smart. And her laboratory focuses on
these belief/placebo effects where if you tell people all
the horrible things that stress do to you in terms of
your memory and cognitive functioning and then you
give them a memory test, they perform well
below baseline. If you tell them that
stress sharpens them in the short term,
and that adrenaline is this powerful
molecule that can really tune up a number of memory
systems, memory improves.

And it's remarkable. And it's consistent. And they've done this for any
number of different things, including food
allergies, for instance. Incredible results. In any case, I'm so glad
you're bringing this up. I take creatine monohydrate,
and I have for years. 5 grams a day. I don't– LAYNE NORTON: And it's great. ANDREW HUBERMAN: And it's great. And I believe it's great. So is there a compound effect
of believing it's great and it actually being great? LAYNE NORTON: Not in this study. So I think the
thing to point out, people will misinterpret that
as creatine doesn't work. And that's not what that says. What it says is, your
beliefs about what it does are probably just as
powerful as what it does. So they actually did a study– and I don't have the
citation, but it was– I think, within
the last 10 years where they told people
they were putting them on anabolic steroids. And wouldn't you know it,
they had better gains– even though they weren't
actually on anabolic steroids, they had better gains than
people that they didn't tell were anabolic steroids.

ANDREW HUBERMAN: Amazing. LAYNE NORTON: And that's
like hard outcomes. Strength, lean body mass,
those sorts of things. So when people say,
well, I wouldn't fall for the placebo
effect, it's like, you don't have to fall for it. If you believe it to be
true, the power of belief is very, very powerful. And as a scientist, I wish,
sometimes, I was ignorant so that I could subject
myself to the placebo effect more often. ANDREW HUBERMAN:
Yeah, absolutely. LAYNE NORTON: So
getting back to, that's just a possible
explanation of, maybe, why. And I'm the same way, like
I get done with a workout, like a resistance training
session, I'm like, I'm ready to eat. Now, if you look
at the literature overall on exercise
and appetite, it's not always
what you'd expect. Consistently, it seems to show
that exercise actually has an appetite suppressant effect. So people don't
tend to compensate at least fully for the
amount of movement they do. And there is some
evidence that– you've probably heard
people say, well, exercise a really poor weight loss tool.

If you figure out
how many calories you should be burning
from it and you do that, you end up getting less weight
loss that you would predict. ANDREW HUBERMAN: I have
a family member who is perfectly happy to eat less,
but doesn't loathe exercise, but dislikes exercise. And they're of healthy weight. But I'm always encouraging
them to exercise more. And so this is an ongoing battle
in our sibling relationship. LAYNE NORTON: Well,
one thing I would say is that, exercise
independent of anything that happens with your body
weight, you will be healthier. So exercise is one of the
only things that will actually improve your
biomarkers of health without even losing weight. So those– it will improve
your insulin sensitivity, inflammation, all that stuff. So everybody out there looking
for a hack to be healthier exercises the hack, right? ANDREW HUBERMAN: Yeah. Crucial point. And our mutual friend
Dr. Peter Attia, I think, has gone on record
several times now saying that of all the things
that one could take– NMN, et cetera, metformin. Regardless of whether or not
one takes those or doesn't take those, that the positive
effects on longevity by way of biomarkers from
regular exercise is– far outweighs all of
those things combined.

Not that those things
don't necessarily work, we're not going through
them in detail now, but that exercise
is by far the best thing we can do for our
health span and lifespan. LAYNE NORTON: Yeah. Absolutely. I 100% agree. And when you're talking
about weight loss, people miss the point
of exercise, I think. There's some work that came
out from Herman Pontzer as well that basically
showed like, well, if you do 100 calories
from exercise, you have a 28-calorie reduction
in your basal metabolic rate in response to that.

So it's kind of like this
constrained energy expenditure model. But what I would say is, OK,
well there's still a net of 72. So it's still OK,
and the other thing is, I think the effects
of exercise on weight loss are actually more due to
what it does to appetite. So if you look at people who
lose weight and keep it off for a number of years,
kind of outliers because most people don't keep
it off for years, over 70% of them engage in
regular exercise. Of people who do not
keep weight loss, like maintain weight loss, less
than 30% exercise regularly. So now that's just
a correlation. That doesn't necessarily
prove causation. But there are some
pretty compelling studies showing that exercise
increases your sensitivity to satiety signals. So basically, you can have
the same satiety signals, but you're more sensitive
to them when you exercise. And there's actually
a really classic study from the 1950s in
Bengali workers where they looked at, basically,
four different quadrants of activity. So you had sedentary, lightly
active, moderately active, heavily active. Basically, based on
their job choice.

And they didn't have
an intervention. They just wanted to track
them and see how many calories did they actually eat. So it was like a J-shaped curve. So the sedentary
actually ate more food than the lightly active
or moderately active. But from lightly active
to heavily active, they almost perfectly
compensated how many calories they should be eating. So to me, that suggests,
when you become active, you can actually regulate your
appetite appropriately or much more appropriately than
if you're sedentary. ANDREW HUBERMAN:
And do you think this has to do with
changes in the brain– brain centers that
respond to satiety signals from the periphery,
and/or do you think it has to do with changes
in blood sugar regulation? What I was taught, and I
don't know if this is still considered true, is that
spikes in blood sugar will trigger a desire to
eat more even though it's kind of exactly the opposite
of what you need when you have a spike in blood sugar.

And there's this
kind of– and we'll get into this when we talk
about artificial sweeteners. This is the idea in mind. I think I adopted, perhaps,
falsely that you eat something that's sweeter, that
tastes really good, and you are suddenly on the
train of wanting to eat more. And I could imagine
how exercise, if it is increasing
the satiety signals, could be working a
number of different ways. LAYNE NORTON: Yeah. I think it's– I think the effect is probably
mostly at the brain level. The effects on blood sugar– the research out there is not
very compelling for blood sugar driving appetite. Now, if you become hypoglycemic,
yes, you'll get hungry, but it's a different kind of
hunger than your normal like, I feel kind of empty and
my stomach's growling. Like those are–
they can go together, but usually like the
hypoglycemia is like, I am hot, I feel like I'm
going to pass out.

You want to eat something not
because your stomach's growling but because that you
just need some fuel. ANDREW HUBERMAN: It's like
you're getting pulled under. LAYNE NORTON: Oh, yeah. Absolutely. ANDREW HUBERMAN:
I've been there when I've done the longer
fasts, something I don't do anymore and
drink a lot of black coffee. There was probably an
electrolyte effect there because coffee as you excrete
sodium and other electrolytes. And then just feeling
like, I needed something. This whole thing
like I need something that's kind of desperation. I never want to be
back here again. Hypoglycemia is
very uncomfortable. LAYNE NORTON: It's not fun. So again, then when they look
at actual randomized controlled trials of implementing
some exercise where they're pretty
controlled environment, they typically see people– if anything, they eat less
as opposed to eating more.

Now, some people, again,
studies report averages. And there's individual
data points. So there are some people who
at least anecdotally report that exercise makes
them more hungry. That's completely valid. It could be their
beliefs around it, it could be a number
of different things, but it's important to
understand that there is individual variability. And I think one of
the things that I've learned to appreciate
more is not trying to separate
psychology and physiology. We do this a lot and say, well,
I want to know the physiology, I don't care about
the psychology of it. And now I'm kind of appreciating
more, psychology is physiology. Like with most things
now, we have kind of the biopsychosocial model. And I'll give you
an example of this. A lot of people get really
caught up with appetite.

And if we could just
suppress people's appetite, that's part of it. But people don't just eat
because they're hungry, they eat for a lot of different
reasons, social reasons, especially. So can you remember the
last social event you ever went to that didn't have food? ANDREW HUBERMAN: No. LAYNE NORTON: Right. If you look at dinner
plates from the 1800s, they're about this big. Now how big are dinner plates? ANDREW HUBERMAN:
The whole buffet. LAYNE NORTON: Right. ANDREW HUBERMAN: Yeah. LAYNE NORTON: There's
situational cues. You're sitting down to watch TV. Oh, grab some popcorn,
grab some snack, whatever. ANDREW HUBERMAN: I
even see this with– you know, how one person
will pick up the phone and then everyone
picks up their phone.

I think there's a
similar effect with food. LAYNE NORTON: Yeah. And same thing, right? Like how many times have
we either done it ourselves or have been experienced
people saying, oh, you should have something–
you should have alcohol, especially, right? People– I was hanging out
with somebody last night and I had a beer and
they just had a water. And I'm like, I feel no need
to try and convince them to do that with me.

You know what I mean? But as humans,
we're hurt animals. We don't want to be
doing something out in isolation on our own. Now, this is a very tenuous,
I guess, belief of mine. But doing things
alone in isolation during ancestral
times, that's going to set off your alarm system. Because if you don't
have other people, you can't protect yourself. So typically, things were
done together in groups. And I think that's a
lot of the reason why we tend to be just tribal in
nature about a lot of things.

So the whole point to that
is, on the list of reasons why people eat, I
mean, I've gotten to the point where I think that
hunger is actually not even the main reason people eat. Stress, lack of sleep– ANDREW HUBERMAN: Boredom. LAYNE NORTON: –boredom. ANDREW HUBERMAN: Yeah. LAYNE NORTON: Absolutely. So unless we can
do something that addresses all those
things, there's a line from a review paper– this review paper
came out in 2011 is by a researcher
named MacLean. And it's the best review
paper I've ever read.

It was called, biology's
response to dieting– the impetus for weight regain. And basically went
through all the mechanisms of these adaptations that
happen during fat loss diets and how biology's response
is to try to drive you back to your previous. And I'm going to
butcher the quote, but at the end of the
study he said, basically, the body's systems are
comprehensive, redundant, and well-focused on restoring
depleted energy reserves. And any attempt or any
strategy for weight loss that doesn't attempt to
address a broad spectrum of these things
is going to fail. And so that's why when people
say, well, just do low carb, you won't be hungry. Look, people don't just
eat because they're hungry. So I think really like
trying to get outside the box and think about these things. And especially, when you
read some of the literature, I recently read a systematic
review of successful weight loss maintainers, which I
thought was really interesting. So they took people who had lost
a significant amount of body weight and kept it off for,
I think, it was three years.

And it basically asked
them questions and tried to identify commonalities. And there were
some things that I expected like cognitive
restraint, self monitoring, exercise. And then one of the
things they said that I found really fascinating
was pretty ubiquitous between people. They said, I had to
develop a new identity. So are you familiar
with Ethan Suplee? ANDREW HUBERMAN: No. LAYNE NORTON: So
Ethan is an actor. He's been in like remember the
Titans and American History X. ANDREW HUBERMAN: I certainly
saw American History X.

LAYNE NORTON: Yeah. So he was very large. He was like 550 pounds. And now he's like
230 and jacked. ANDREW HUBERMAN: Well,
5– he was how many– LAYNE NORTON: 550 pounds. ANDREW HUBERMAN: Wow. LAYNE NORTON: And he
has– whenever he puts up post on his Instagram of
him training, it'll say, I killed my clone today. And I asked him, is this
what you're talking about? Creating a new identity. And he said, this is exactly
what I'm talking about. Because I had to kill who I was. Because there was
no way I was going to be able to make long
term changes if I just didn't become a new person.

Because I mean, and
addicts talk about this. Like people who are alcoholics. They had to get new friends. They had to hang out
at different places, because their entire
life had been set up around this lifestyle
for alcohol. And I would actually argue
that eating disorders or disordered eating patterns
is much harder to break than other forms of addiction. And you think about
food addiction. Well, in some ways, bulimia and
anorexia are still addictions. You can't stop eating. Like if you're alcoholic,
you can abstain from alcohol.

If you become addicted
to say, cocaine, you can abstain from that. You can never abstain from food. And so now imagine
telling a gambling addict, well, you've got to play this
slot a couple of times a day but no more. Like that's really challenging. So yeah. I just– like all
this stuff, it's so important to be comprehensive
with how we treat these things. ANDREW HUBERMAN: Right. These are incredibly
important points. And to my knowledge,
I don't think anyone has really described
it in a cohesive way the way that you're doing here. So important for people
to understand this because obviously,
as a neuroscientist, I think the nervous system
is creating our thoughts, our thoughts and feelings
are related to psychology, and therefore, of course, our
physiology and our psychology are one and the same. It's bidirectional. Now, nowadays, there's a lot
of interest in brain, body, and particular gut– brain axis and we
can talk about that.

But I really
appreciate that you're spelling out how there are
these different variables. Each one can account for a
number of different things. Exercise clearly has a
remarkably potent effect– both during the exercise
in terms of caloric burn and overall health
and biomarkers. And then this is
wonderful to learn that it can increase the
sensitivity to satiety signals. I think that makes–
at least in my mind, places very high on the
list of things that people should absolutely do.

But there are other factors too. And the identity
piece is fascinating. It reminds me also– your
story reminds me also of David Goggins who is– he talks about his former
very overweight self almost as if it was
a different person. And he uses language that
I'm not going to use here. But you know what? I've met David, know David
a bit, and his every bit is intense and driven as
and a remarkable human being as he appears
to be online. He is that guy. But it does seem like he
had to more or less kill off a former version of himself and
continues to do that every day.

And I think what your point
about this other fellow who does it through a similar
process, the word "today" seems to really matter. It's not like you defeat this
former version of yourself and then that person
is buried and gone, you said, you know, I
killed my clone today, and that's the way that
David talks about it also. So this is a daily process. And I think this is not just a
small detail in time together all these things. I think that what
you are describing is fundamental,
because we can pull on each one of these
variables and talk about each one of them. But at the end of the day,
we are a cohesive whole as an individual. Sorry. You were about to say. LAYNE NORTON: That gets actually
into one of my favorite topics, which is, why do we have such
a hard time with losing weight but more so keeping it off? Because of obese people, six
out of every seven obese people will lose a significant amount
of body weight in their life.

So why do we still have
an obesity problem? They don't keep it off. Why don't they keep it off? When you look at the
research, basically, what it suggests is
because people think about, I am going to do a diet, and
I'm going to lose this weight, and they do not give any thought
to what happens afterwards. It's like think about if you
have some chronic disease or a diabetic. You can't just take insulin
once and that's it, right? You've got to take it
continuously, otherwise, you're going to have problems. If you do a diet and you
lose 30 pounds, fantastic. But if you then just go
back to all your old habits, you're going to go back to
where you were, if not more. You can't create a new
version of yourself while dragging your old habits
and behaviors behind you. So what I'll tell people is– because people say, well,
I'm doing a carnivore diet or I'm doing this
diet or that diet.

And I'll say that's fine. Do you see yourself doing that
for the rest of your life? And if the answer is
yes, if you really believe that that's going
to be sustainable for you, and plenty of people, low carb,
intermittent fasting, whatever, they say, I felt easy. I could do this forever. Great. If you're going to lose weight,
you have to invoke some form of restriction– whether it is
a nutrient restriction like low carb, low fat, a
time restriction– intermittent fasting any form
of time restricted eating, or calorie restriction– tracking macros, whatever. So you get to pick the
form of restriction. So pick the form
of restriction that feels the least restrictive
to you as an individual, and also do not
assume that it will feel the same for everybody else
because I made this mistake. Whereas it's like,
I track things. And so I allow myself to
eat a variety of foods, I allow myself to
eat some fun foods. But I track everything, and
I'm able to modify my body composition and be in
good health doing that. Now, doesn't feel hard for me.

Part of it, I've just
been doing it for so long. But to other people,
that's very stressful. They don't want to– they say, well, I'd rather
just not eat for 16 hours. If that feels easy for them,
do that because the one thing that– there was a couple of
meta analysis on popular diets. And basically, what
they showed was they were all equally terrible
for long term weight loss. But when they stratified them
by adherence– and none of them were better for
adherence overall.

But when they
stratified people just according from lowest
adherence to best adherence, there it was a linear
effect on weight loss. So really what it
says is, what is the diet that's going to be
easiest for you to adhere to in the long term and you
should probably do that? And people– again, this is
where I step back and take the 10,000-foot view. Somebody will say,
well, I'm going to do ketogenic because I want
to increase my fat oxidation and I want to do this. And they're talking about
all these mechanisms and everything. And that's great. Can you do it for the
rest of your life? Is this going to be something
sustainable for you? And if the answer
is, no, you probably need to rethink what your
approach is going to be. ANDREW HUBERMAN: Incredibly
important message. Basically, that. If I could highlight– if there
was a version of highlight or boldface and underline
in the podcast space, I would highlight– boldface and
underline what you just said.

And for those of
you that heard it, listen to it twice,
and then go forward because it's absolutely key. I think it also explains a lot
of the so-called controversy that exists out there. I think it also crosses over
with the placebo effect. I almost want to say,
pick the nutrition plan that you think you can stick
to for a long period of time, ideally forever. And pick your placebo
too, because there is a lot of placebo
woven into each and every one of these things–
intermittent fasting, keto. Probably even vegan versus
omnivore versus carnivore. LAYNE NORTON: Well, they even
talk about the diet– honeymoon period where you go into a
diet and you're all fired up about it and like
you're very adherent, and then what happens,
with every single diet without exception
in research studies is once you get past few
months, adherence just starts waiting and going off.

ANDREW HUBERMAN: Here
we are really talking about a form of relationship. I'm not saying that
to be tongue in cheek. Actually, we had a guest early
on in the podcast, Dr. Karl Deisseroth, he's a psychiatrist
and a bioengineer at Stanford. Tremendously successful. Alaska award winner, et cetera. And he talked about love as a
sort of an interesting aspect of our psychology
where it's a story that you co-create with
somebody but that you live into the future of that story. When you pair up
with somebody that was referring to romantic
love, that there's this sort of mutual agreement
to create this idea that you're going to live into. So it's not just about how
you feel in the moment, it's also that you project
into the future quite a lot.

I'm seeing a lot of
parallels with a highly functional and effective diet. And I love it. I'm not setting this
parallel up artificially, I'm setting up because I
think that ultimately it boils down to what you
said earlier, which is that the brain and our
decisions about what we are going to stick to are
tremendously powerful. LAYNE NORTON: I think one thing
I will say is keep in mind, when you look at the research
data, the meta analyzes on say, time-restricted eating versus
none, when calories are equated, doesn't seem to
be a difference in weight loss, fat loss, and most
biomarkers of health. Same thing for low
carb versus low fat. Fewer quick calories
and protein. There was a meta analysis done
by Kevin Hall back in 2017 where they looked at the– and
again, actual loss of body fat.

And another important
point was, I think there was 22 studies in this. But all of them provided
food to the participants That's important because
that ensures that adherence can be much higher
in those studies whereas various free
living studies, sometimes, you can see funky results. ANDREW HUBERMAN: People
are sneaking food or they're just not really– LAYNE NORTON: It's
very difficult– ANDREW HUBERMAN:
–eating the way that the study would
ideally have them eat. LAYNE NORTON:
Unless the person is getting like continuous
support– like, studies where they
have a dietician talk to people like every
week tend to actually have pretty good adherence. I mean, that's expensive
to have done the study. And again, like what limits
studies, money, money, and money. But the low carb versus low
fat, protein, and calories are equated, basically,
no difference in fat loss. Now, some people get
upset about this. But it's like–
what to me, that's like– this is great because you
get to pick the tool you want.

The one tool, it
doesn't seem to be that much better than another. So pick the one
that works for you. Whatever lever
you've got a pull, you've got a bunch
of different options. ANDREW HUBERMAN: You
mentioned picking something that you can stick to
for a period of time. Is there ever a case
for someone saying, look, I like to eat low carb
or even keto for six months and then switch to a
more standard omnivore caloric maintenance type
diet and then switch back? Is there any downside
to doing that for sake of health or
weight loss over time, or weight maintenance over time? Because I realize not everyone
is trying to lose weight.

And I definitely
want to talk about, at some point, how to
eat to maintain weight. Because I think there are
a significant fraction of people out there who
are trying to do that. Yeah. Is there any downside
to being a dabbler? Keto for a few months
and then omnivore for a few months, et cetera? LAYNE NORTON: I think that's
actually a great thing, especially to like,
maybe, find what you feel is easiest for you. But in terms of as a
strategy, I mean, I guess, some people just might
get into dopamine but like, oh, change
and get something new. And you feel a little bit
more positive about it. ANDREW HUBERMAN: And
do partner model. LAYNE NORTON: Yeah. Yeah. Exactly. So I don't think it's how I
would usually set things up initially for somebody,
but if somebody said, hey, I just like to have some
variety and change it up, as long as they're still like– their behaviors and they're
doing portion control or whatever it is, and
they're able to sustain a calorie deficit or depending
on whatever their goal is, I don't think there's
really any downside to it.

I do think the one thing
to keep in mind is, when you look at like
going between extremes, so like low fat to low
carb or vise versa, there can be, in that
transition, period a little bit of weirdness for lack
of a better term. Like for example, if you've
been on a ketogenic diet and all of a sudden, you move
to a higher carb diet, you'll be basically
insulin resistant for just a short period of time. Now, is that going to
cause any health problems? Probably not in the long term,
especially, if you're still controlling calories.

But just because your body has
like upregulated these systems, dealing mostly with fat
and glucose production rather than glucose
metabolism, so now if you start taking glucose
or carbohydrate back in, like for example, you get
somebody– or a glucose tolerance test after
they've been on keto, they'll do pretty
terribly at it. But that doesn't last that long. ANDREW HUBERMAN: About how long? LAYNE NORTON: A few weeks. ANDREW HUBERMAN: I think that's
important for people to know, because I have a feeling
during those first few weeks are the period of time
when a lot of people go running back to what
they were doing previously. Which is not to say that they
shouldn't, but I've certainly done that. I've tried very low
carbohydrate diet, and I would have assumed– and now I know I'm
completely wrong, but I assumed that I was
so carbohydrate starved for so long that my
insulin sensitivity, which is a good thing,
by the way folks, would have gone
through the roof, and I would be able to just
sponge up every bit of glucose that I would have ingested
through carbohydrate.

So I did indeed switch over. And I felt like I had
pretty terrible brain fog. I even got some jitters. And I thought, what is this? My blood sugar was low
before, and now my blood sugar should be in more
moderate territory. But based on what
you just said, I'd upregulated the
enzymes and systems in the body for fat
metabolism on the keto diet and then switching over– there was basically a ramping up
of the molecules involved in– presumably in glycolysis. LAYNE NORTON: Transition period. I mean, think about if you
haven't weight trained before and you start weight
training, you're going to feel pretty terrible.

Like you're going
to be sore and stiff and all that kind of stuff. But I will say, you aren't
necessarily wrong in what you said about being
more insulin sensitive, because it depends on how you
measure insulin sensitivity. So if you measure with something
like fasting blood glucose or fasting insulin
or even HOMA-IR, those tend to be pretty
good on low carb. But then if you do it all
glucose tolerance test, it tends to be pretty bad. And so it depends on
your specific measure. So I think that
the idea that keto makes you glucose intolerant
or insulin resistant, I think, again, it's
just a transition period.

And I'm not too
worried about it. But it is something
important to keep in mind. And one of the reasons
like if somebody was to transition out
of keto, typically, if I'm working with them
or one of our coaches are working with
them, we'll kind of instruct them to do it like
slowly and systematically over like a four to
eight-week period. That way, hopefully, they're
not having that period of two weeks where
they're like, oh, man, why do I feel so terrible? ANDREW HUBERMAN: A
very important point. I want to go to the other end
literally and figuratively and talk about gut
health, because up until now, and certainly– LAYNE NORTON: I see what
you did with that pun.

ANDREW HUBERMAN: And certainly
in the last few minutes, we've been talking a lot
about top-down processes. The brain, the psychology,
placebo effects, but the very real
aspects of those, not that I can imagine 2,000
calories, 1,000 calories and somehow change the
law of thermodynamics. Can't do that. But we've been
top-down in integrating a lot of different
ideas into weight loss maintenance and weight gain. But gut health, at least
the more popular studies on gut health, have blown a
lot of things out of the water. For instance, this idea that
you could take obese mice and literally give them fecal
transplants from lean mice, and yes, that sounds
like what it sounds like. Fecal transplants definitely
inserted through the same end in which it comes out.

And I point that out because
a lot of people have asked me that they– and it was kind of
scary to me, I thought, yes, this is not about
ingesting feces, this is– they literally do a transplant
of these from lean mice into obese mice and the
obese mice get lean. And yes, this has
been done in humans. Limited number of studies and
observed some pretty impressive effects on weight loss
that I have to assume could be related
to placebo effect. They might have told these
obese people, hey, look, you're going to get lean
through this fecal transplant from lean people. But more likely,
it had some effect on their core physiology. I don't know which
aspects although, I can speculate which ones. And they became leaner. They lost weight. And that is, in some sense,
miraculous, especially given the important role of psychology
and exercise and satiety signals, because I'm going to
assume that they controlled for a number of those
other variables, although no study is perfect.

What are your thoughts
about gut health as it relates to metabolism,
energy utilization, and balance? LAYNE NORTON: Yeah. So the first thing I'll say is
I'm not a gut health expert, but I will– I feel relatively comfortable
talking about it based on conversations I've had
with people who are experts– one being Suzanne
Devkota who's– you're familiar with her? ANDREW HUBERMAN:
Well, she's sort of a phenom in this area
from what I understood. LAYNE NORTON: So
she was actually doing her masters when I was
doing my PhD in Lehman's lab. So she was one of my lab mates. ANDREW HUBERMAN: Terrific. LAYNE NORTON: And the
other thing to say is, even gut health experts,
and Suzanne will tell you this, they're like, talk
to me in 20 years.

We just know so little. I think that's an overall thing
that people don't understand is the scientific consensus
moves very, very slow, probably for good reason. Because if we just flipped
our scientific consensus based on one study, I mean,
it would be a mess. So it's going to take
time before we really understand the implications
of the gut and what it means. So when it comes to weight
loss, there probably is a role in there.

I mean, we've seen that
there's something going on. Now, whether that's– is
it something where a gut microbiome make makeup that's
more obese resistant, perhaps, it extracts less calories
out of the food you eat. Or perhaps, it's elevating BMR. Although, I think that that's
probably somewhat unlikely. ANDREW HUBERMAN: Do you
think it could impact the way satiety signals are? LAYNE NORTON: So that's– ANDREW HUBERMAN: I mean,
back to the brain again. LAYNE NORTON: –so that's–
we know that there's a link in the gut brain axis. And so my suspicion
is that it probably is working via
appetite regulation. So I mean, if we look at
the most effective obesity treatments out there,
which is like semaglutide, I mean, you
consistently see a 15% on average loss of body
weight, which is massive and people keep it off. That is a GLP-1 mimetic
which is a gut hormone. And it, basically, just is a
very, very powerful appetite suppressant. ANDREW HUBERMAN: Well, I
guess I'm interrupting, but hopefully, with a purpose.

There's this really
interesting study. And it's in mice,
admittedly, but published in a neuroscience
journal recently. And basically, the takeaway
is that like so many things in neuroscience, the GLP-1
works in two parallel pathways. In the brain, it seems
to impact neurons in the hypothalamus
that control satiety. So exactly what you're saying. And in the gut,
it seems to create an activation of the
mechanosensors in the gut.

So the perception is that the
gut is full even– or fuller. I should say, not
full, because I think people who take
semaglutide don't feel bloated. I don't know, they might. But that one feels as if
their gut is actually fuller because these mechanical
sensors that send– stretch are sending signals
to the brain, oh, I actually have some food. I'm not empty down there. LAYNE NORTON: Right. ANDREW HUBERMAN: Anyway,
I'm tickled by this result mostly because every time I
hear about a drug or a molecule having an effect, we think it
has an effect at one location. But it's kind of interesting
that, especially for something like appetite regulation,
that it would be impacting body and brain in parallel. Anyway, forgive me. LAYNE NORTON: That's great. ANDREW HUBERMAN: You can tell
I'm really excited about this. And here you are telling
a neuroscientist, me, that a lot, perhaps,
circles back to these brain mechanisms of satiety. LAYNE NORTON: Yeah. I mean, I think that– and especially looking at
the research on leptin, you we used to think,
OK, metabolism is mostly like liver-based
and then there's metabolism in the adipocyte
and skeletal muscle.

But none of this stuff
exists in isolation. There's so much crosstalk
between these pathways. And that's– when we
get into mechanisms– though one of the things
I love mechanisms. But one of the
things I tell people is keep in mind that when
you're dealing with an outcome, like when I say
outcome-based, we're talking about physical outcomes
like weight loss, fat loss, changes in blood
markers, whatever, though that is the
summation of thousands of different mechanisms.

So sure, sometimes, you can
affect a mechanistic pathway, and you get straight down the
line outcome, but not always. Whenever you make a treatment
or anything into the system, it's like throwing
a pebble in a lake. It creates ripples. And we don't always know
what those are going to be. And that's why– I mean,
we've seen certain drugs, what works on this pathway. And then they list off
all the side effects. And you go, well, how would it
create that many side effects? Because nothing–
for the most part, they don't just
work in one place. There's multitude
of places it works. And to your point
about semaglutide and the effects on
mechanical sensors, it's probably why
a lot of people report actually low grade nausea
when they're using semaglutide. Because of that. Because if you're– that feeling
is usually not like a real comfortable feeling, but I mean,
it will get you to not eat.

So I think there's absolutely
likely a connection, but we haven't fully
elucidated how that works. And we think about how
complicated the gut is. I think I heard
something like there's more cells in our microbiome by
far than there are in our body. So we're actually more– in terms of a cell
per cell level, we're actually more bacteria
than we are eukaryote. ANDREW HUBERMAN: There's
Justin Sonnenburg who's one of the world
experts on microbiome. He's in the lab upstairs
from mine at Stanford. And he has this idea– it's just an idea that because
we are indeed more bacteria than we are cells, the
question is, who's the host and who's the passenger? LAYNE NORTON: Yeah. ANDREW HUBERMAN: Maybe,
we are just– maybe they're exploiting us to take
them around and interact, because they interact
and grow on one another. And so this idea that
this freaks people out, Lex Fridman will love this. That maybe human beings
are just actually the vehicles for the microbiome
and not the other way around. Anyway, kind of a scary thought.

Do you do anything specifically
to support your gut microbiome? Are you a probiotic guy or a
fermented foods guy or a fiber guy? LAYNE NORTON: So– again, I'm
going to kind of go straight down the line from
what I've heard from Suzanne and other experts. So if you want to improve gut
health, one of the biggest levers– the three biggest
levers you can pull is not eating too many
calories, exercising– there is a connection
between exercise and the gut, and fiber. So it is– of the
things we know, dietary fiber seems to
positively impact the gut because it is what's
called a prebiotic. So your gut microbiota can
take, especially, soluble fiber. Although, there's actually some
evidence, at least in mice, that they might be able to use
some insoluble fiber as well. I think Suzanne was doing a
study looking at hemicellulose and actually seeing that
some, like specific forms of microbiota, flourish with
hemicellulose suggesting that they may
actually be getting some kind of fuel out of it,
which is really interesting. But again, in mice–
so just a huge caveat.

So your gut
microbiome can produce these short chain fatty acids
by fermenting the soluble fiber. And there's quite
a bit of evidence that these volatile fatty
acids, which can be then actually reabsorbed
into the liver, that they have some
positive effects. Like for example, butyrate. When they've done
butyrate supplementation, they've actually seen positive
effects on insulin sensitivity. So what we seem to understand
is that more diversity seems to be better, fiber
seems to be positive, prebiotics seem to work
much better than probiotics. ANDREW HUBERMAN:
Supplemented prebiotics. LAYNE NORTON: Yes. So the problem with
most of the probiotics is they're typically
not concentrated enough to actually colonize. And even if you do colonize,
what happens is like, let's say you colonize
some microbiota that you didn't really have much of. If you're not fueling it
with the appropriate fiber, it's not going to stay anyway,
because it's essentially going to starve. So the research seems to
really clearly suggest that eating enough fiber,
which is, again, a prebiotic, that that is a better way
to get a healthier gut per se than probiotic.

ANDREW HUBERMAN: What
fiber sources do you use? And I think– I mean, I realize
there's a huge array of choices out there, but people
will want to have some ideas as to how
they could, perhaps, mimic what you're doing. LAYNE NORTON: Yeah. And I would just say diversity. So there's various evidence
from various different fiber sources– fruits and vegetables,
obviously, grains, some whole grains, some cereals,
and then various other sources. So this is one of the
things where we don't really have a good idea. If you know this
one source of fiber is better than another
source of fiber, we just know that fiber
overall is pretty good.

And one thing I'll
tell people is like if you want a
longevity hack, I mean, fiber is kind of
the longevity hack. If you look at some of
these cohort studies, there was actually a recent
really large meta analysis of over a million subjects. And basically, what it showed
was that for every 10 gram increase in fiber, there
was a 10% reduction in the risk of mortality. And that extended, specifically,
also to cardiovascular disease and cancer. So one of the things
I'll tell people when they get like
really into whether it's intermittent fasting or
all these other things, say, that's great, that's great. Are you eating like over
50, 60 grams of fiber a day? ANDREW HUBERMAN:
Conceptualize 50 or 60 grams.

So if I were to eat
like a– let's just say, a quarter plate of
broccoli and the broccoli isn't stacked to the ceiling. The broccoli is just
reasonably stacked on there. Approximately, how many
grams of fiber is that? If it's like two
cups of broccoli. There's a lot. LAYNE NORTON: Yeah. So like 200 grams of broccoli,
per se, would probably be like 5, 6 grams of fiber. ANDREW HUBERMAN: And I need
to get how much per day? LAYNE NORTON:
Well, I would say– ANDREW HUBERMAN: Ideally. LAYNE NORTON: –typically,
what the recommended dose is is 15 grams
per 1,000 calories intake because if you're
eating low calories, it's difficult to
get enough fiber in. But based on– and again,
these are cohort studies. But you can't do 20-year
long randomized human control trials, unfortunately. That doesn't really appear
to be a top end, at least for the benefits of fiber. It probably boils down to
how much you can tolerate without feeling uncomfortable. Because if you're eating
like a ton of fiber, I mean, at some point, it's not
going to be very comfortable.

ANDREW HUBERMAN: Yeah. Exercise becomes
uncomfortable or hazardous. Yeah. LAYNE NORTON: And I actually a– kind of touching on that
because I think it is important. A lot of people have kind of– in the carnivore community said,
well, you don't need fiber, you poop just fine without it. And I'll always say, well,
pooping is the last reason to have fiber. Like yes, it does help. It does seem to make
elimination easier, you can do it more frequently,
adds bulk to stool. But that's not why
you should eat fiber. Why should eat fiber is because
of the effects of mortality. And some of the pushback
will be, well, this is healthy user bias. And what I'll say is– ANDREW HUBERMAN: Meaning,
healthy people do this and therefore it's working.

LAYNE NORTON: Healthy people
eat more fiber and therefore– ANDREW HUBERMAN: OK. Yeah. LAYNE NORTON: And I mean, yeah. There's something to that. But if it was just
healthy user bias, typically, you would
see some disagreement between the studies. And a great example of
that is like red meat. So not every study shows
red meat has an association with cancer and mortality. There's differences depending
on the population use, depending on what they define
as high red meat, low red meat, whether it's
processed, unprocessed. But I have not found
a study on fiber and cardiovascular disease
and cancer and mortality where it did not show
improvements from higher fiber. So to me, that suggests
that that effect is real.

And so again, as much fiber
as you can get in comfortably, I would try to do
it because it seems to have some really
powerful effects and is good for
the gut microbiome. The other thing that
may be a consideration for the microbiome is
there's some evidence that saturated fat may not be
great for the microbiome. That it reduces the
prevalence of some of the more positive
strains of bacteria. And that appears to be not so
much from the saturated fat itself but from the
bile end products that combine with
saturated fat seems to have a negative
effect on some of these more healthier
forms of gut microbiota. But again, this is
really difficult because we don't
even know necessarily yet which species
of gut microbiota are positive or negative.

And that's– I mean, this gets
into some of these studies where they may
call it dysbiosis. Sounds scary, but dysbiosis
just means that the gut changed. ANDREW HUBERMAN: Right. LAYNE NORTON: It
doesn't necessarily– it doesn't tell you
anything qualitative about whether the
change was bad or good. And so these are
just things, I think, we need to keep in mind when
we talk about this stuff. That this stuff is still
very much in its infancy. But in terms of the
big levers, I mean, it's pretty much
fits with what we know about a healthy lifestyle. Exercise, don't eat too much,
consume a good amount of fiber from diverse sources. ANDREW HUBERMAN: Fantastic. Fantastic because
it fits with what I like to think of as the
center of mass of evidence. And I'm starting to get
some window into what your process is around selection
of studies and no one study being wholly, but
when you look at, as you mentioned, all
the studies on fiber having a positive effect
to some degree or another, it's pretty hard to refute that
there isn't something really interesting there.

LAYNE NORTON: And one thing
I'll tell people is like, one study– I mean, sometimes
I'll change my opinion based on a single
study when it's really well done and very powerful. But usually, one
study is just going to move me just a little bit. And then maybe, if
another one comes out, maybe a little bit more. And then like very slowly,
I'm going to get some– I mean, my experience
with LDL cholesterol, that's something I changed
my mind on a while back.

When I was younger, like circa
2005 getting into grad school, the prevailing thought was,
well, it's not so much the LDL, it's the ratio of LDL to
HDL, that's what matters. And probably about
five years ago– and I was pretty strong
about that opinion, and then five years ago
looking at these Mendelian randomization studies, I went,
I can't hold this position anymore.

ANDREW HUBERMAN: What is
your revised position on LDL? LAYNE NORTON: So if you
look at the research, HDL is important because it's
a marker of metabolic health. If you have high
HDL, it suggests that you are metabolically
quite healthy. You very rarely will you
have high HDL and high CRP, which is inflammatory marker
or dysregulated blood glucose. Almost exclusively,
people who have high HDL will have good biomarkers
of metabolic health. But if you take
drugs that raise HDL, it doesn't reduce your risk
of cardiovascular disease. In Mendelian
randomization studies, which Mendelian
randomization basically uses natural randomization. So some people are,
in the case of HDL, naturally higher secreted
or naturally lower secretions of HDL. And we talked about
how– you can't really do a 20-year human
randomized controlled trial. And when you're trying
to examine something like heart disease, I mean, that
is a lifetime exposure issue. It's very unlikely
that you're going to pick out differences between
treatments in two years or even five years. I mean, people don't develop– typically, don't
develop heart disease until they're in their
50s, 60s, and 70s.

What Mendelian randomization
allows is to say, OK, we have these people who
naturally secrete more or less. So we can stratify those and
look at what is their risk. So if you look at people
who are low series of HDL versus high secrete
of HDL withholding some of the other key
variables consistent like LDL, you don't see an effect
on heart disease, really. ANDREW HUBERMAN: Of LDL. LAYNE NORTON: Of HDL. ANDREW HUBERMAN: Got it, OK. LAYNE NORTON: But
when you look at LDL and you look at the
lifetime exposure to LDL, it is like a linear
effect on heart disease.

And we know that it's
actually not so much LDL, but it's more
apolipoprotein B. But that tends to track with
LDL just in general. And if you look
at the mechanism– I mean, we know that LDL can
penetrate the endothelium, so there's the
mechanism is present. If we look at the
epidemiology, it supports that it's an
independent risk factor, and then, again, these
Mendelian randomization studies where we can
look at people's exposure over a lifetime, and then we
see that linear dose-dependent effect. To me, that was
convincing enough to change my mind on
that particular topic. And then if you look at
some of the Framingham data, look at high– if you like stratify, like
high HDL versus low HDL, both groups looking at
high LDL and low LDL. So if you have
high HDL, low LDL, you will still be lower
risk factor than somebody who is high HDL and high LDL. ANDREW HUBERMAN: So
the ratio does matter. LAYNE NORTON: The
ratio does better. Same thing with inflammation. If you look at people who are
low inflammation, low LDL, they'll have a lower
risk than people who are low inflammation, high LDL.

So again, that was sufficient
for me to change my mind. But it took– it was like
not just one study came out. It was, OK, then there was
another study, and then another study, ans then another
study, and at a certain point I go, OK, well, now, I
either have to change my mind or I'm, basically, just going
to be cognitively dissonant and say, nope, I don't
believe all that. And so I think that's one of
the things to keep in mind. People will say, oh, are you
saying this is a bad study? Very rarely will I call
something, a bad study, because data is just data. But the issue becomes
how it is presented and how broadly it's applied
in the mainstream media or by people on– fitness influencers. And what I'll do
is try to step in and say, OK, let's consider
x, y and z as well. And then it's not a bad
study, but let's just be careful about how broadly
we apply the interpretation.

ANDREW HUBERMAN: Yeah. Well, and I think you are in
a very unique and important position to be able
to place things into their proper
context because of this, for lack of a better
word, holistic view of how the psychology
placebo effects also core physiology relate
to one another. And so on. In fact, I think that your
training as a biochemist and then training as in
nutrition with somebody who– Don Lemon, who was pushing
you to focus on outcomes, I think that's a
beautiful capture of the continuum at which
one can look at something.

Because for those of
you who don't out there, you know a lot of laboratory
studies on mice and humans, for instance, in the
realm of biochemistry or in vitro studies, you'll
see a change in some molecule can be quite dramatic. And then the assumption
is, oh, you just take– you take the
drugs that will change that molecule in a
particular direction, and then you'll get the effect
you want at the whole organism level. The person will lose weight,
the person will gain muscle, the animal will not have
Alzheimer's, et cetera. But it just doesn't work that
way because of the redundancy, and this interplay. LAYNE NORTON: Well, a
great example of that is, so my research was
actually in rodents.

All my studies on protein
metabolism, and leucine, in particular, is
what we were studying. Well, we know if
you give leucine, it increases muscle
protein synthesis. But we also know if you
supplement with leucine, people don't get more muscular. ANDREW HUBERMAN: I
was about to say– LAYNE NORTON: So as always– ANDREW HUBERMAN:
–all you have to do is supplement with leucine? LAYNE NORTON: Right. Right, right. And so how is that possible? Muscle building is not
just protein synthesis. It's also the balance between
synthesis and degradation. And degradation just happens
to be very, very difficult to measure. But a great example– and again, one of the
cool things about my PhD was actually changed
the way I ate, which I think is interesting. So before, I had been like,
I eat eight meals a day, eat every two
hours, try to keep– ANDREW HUBERMAN:
Eight meals a day? LAYNE NORTON: Yeah when
I got to grad school. ANDREW HUBERMAN: In
order to get that 30 grams of protein per meal? LAYNE NORTON: Get that
amino drip going in was the idea, right? Like just have an IV
hooked up of amino acids.

ANDREW HUBERMAN:
Not really, folks. LAYNE NORTON: Not really, yeah. But that was the concept. But the first study that I did,
we, basically, looked at OK, a lot of people had measured the
amplitude of protein synthesis in response to a meal. We wanted to see, how
long does this last and where does it peak, right? And so my thought was, OK. Well, it'll probably
track with plasma leucine. For those that are
not familiar, leucine is the amino acid that
is almost exclusively responsible for increasing
muscle protein synthesis when you eat protein. So it's one of the
branched chain amino acids. So we wanted to see, OK, how
long does this effect last? So we fed these
animals whey protein, and again, I thought, OK, well,
however long plasma leucine, stay up that, will be how long
protein synthesis stays up. And so we got the protein
synthesis data back, and it was peaked at
90 minutes– or sorry.

Peaked from 45 to
90 minutes and, then was back down to
baseline by 180 minutes. And so when I went to do
the plasma leucine analysis, my shock was, at three hours,
plasma leucine was still plateaued out. And then I said,
OK, well, when I look at the initiation factors,
that will show me something. So for those not
familiar, this is part of the mTOR signaling pathway. So one of the–
two of the targets of mTOR, when it's stimulated–
and leucine stimulates mTOR. Two of the targets of mTOR are a
protein compound called 4E-BP1. And then another one is called
a ribosomal protein S6K. So I don't want to get
into the specifics about it because it's going
to be on the scope.

But basically, when these things
are phosphorylated by mTOR, it increases the rate of
translation initiation, which translation initiation
is, basically, the process of the ribosome
hooking on to the mRNA and then starting
protein synthesis. So I was looking at
the phosphorylation of 4E-BP1 and RPS6. I was like, OK,
well, I'll probably see these things come
down in three hours. Still plateaued. And so then it was like,
what's going on here? So I actually kept rerunning
the data and rerunning the data and rerunning the data. And I'll never forget, I
went into Lehman's office. And this is like six
months after we've done this study, because
this analysis takes time. I was like, so where are we
with this duration study? I said, well, I just got to
run the plasma data again because it's not right. And he's like, well,
why is it not right? And I said, well,
it just doesn't make any sense you know. And I kind of went through,
he's like well, describe to me your technique. How are you doing this? And I described it,
and he said, well, how is your standard error? And I told him what the
numbers were, he said, it sounds like it's good data.

He said, it sounds
like you are trying to get the data to
fit your conclusion and you need to change your
conclusion to fit the data. And that statement– ANDREW HUBERMAN: This
is why we do PhDs. LAYNE NORTON: This
is why, yeah– ANDREW HUBERMAN: You
need an advisor– LAYNE NORTON: This is why I
am so skeptical of everything, because I have had so many of
my ideas crushed by my own data, right? So we actually ended up– this kind of effect,
this phenomenon is called muscle protein
synthetic refractory period.

So basically, like once
you trigger the system, runs for a defined
period of time and then it takes time
to, essentially, reset for lack of a better term. It's also been referred to
as the muscle full effect. So I looked at that
and said, why am I eating every two hours then? And there was even a study
out of Wolf's Lab back in '99, I think, where they infused
essential amino acids for six hours.

Protein synthesis went
up, peaked at 60 minutes, came back down 120, and
never went back up again. ANDREW HUBERMAN:
Maybe I'm being naive. But I would have thought that
if protein synthesis goes up and then comes back down,
that eating more often would be exactly the thing you would
want to do if your goal was to get increased protein
synthesis because you'd be pinging the
system periodically. LAYNE NORTON: But the problem
is, the plasma amino acids are still elevated. ANDREW HUBERMAN: So
it's, essentially, like eating the whole way
through from the perspective of leucine. LAYNE NORTON: From
the cells, yeah. ANDREW HUBERMAN: Got it. LAYNE NORTON: So that was
one of those things where I said, you know what? I'm actually going to eat
less often, because if I'm eating in three hours
later, I've still got capped out plasma amino acids. And we looked at
all kinds of stuff. We looked at intracellular
leucine just to make sure that wasn't falling off, it wasn't.

We looked at all the plasma,
essential amino acids because we were thinking,
well, maybe protein synthesis is sucking some of these
amino acids out of the plasma and they're dropping
and that's causing it to short circuit the system. That wasn't the case. It just– essentially,
what the evidence suggests, I think we're the only
ones to show this so far. So I'm not ready to say
that this is a real effect, because I hold out the idea
that data artifacts do exist and you can't be totally sure.

But we saw an
increase in AMP kinase around this mark where protein
synthesis started falling off. And we also saw a decrease
in intracellular ATP. And protein synthesis is
an ATP-dependent process. And so what we think
might be happening is, you're consuming
protein and you're– you're increasing muscle
protein synthesis, and then at a
certain point, it has enough effect on your energy
metabolism in your cells that it short– not short circuits it,
but it cuts it off, right? So again, we're the
only ones to show that. That I'm aware of. And that was again, in rats. So I always talk about data. Like, there's data I'm
willing to bet my toe on, my foot on, my leg
on, and my life on. I'd probably barely bet the end
of my little toe on that one. I'm not quite sure. But it's interesting
nonetheless. So– ANDREW HUBERMAN: A
proportional wait here. LAYNE NORTON: –that's a
great example of, OK, we're looking at this mechanism
of mTOR signaling, and if we just looked
at that, we'd say, oh, well, protein
synthesis is going to stay elevated for past three hours.

But that's not what we saw. So yeah. I think, it's, again, that's
why I really try to get people to say, well, let's– mechanisms are important. And especially, if
you're seeing an outcome, it's important to
identify mechanisms that may explain that. But let's step back
from the mechanisms from trying to chase mechanisms. And let's look at
chasing outcomes in terms of what we
recommend to people. ANDREW HUBERMAN:
Excellent point. In terms of chasing outcomes,
a number of people I know are interested in weight
loss or weight maintenance. And several times throughout
today's conversation, we've come back to this
issue of satiety signals. Whether or not there are
brain-based, body-based, or both. Not wanting to eat
more is a great way to maintain or lose
weight because you simply don't want to. I heard you mention
earlier that protein and maybe specific types of
protein or sources of protein may provide better
satiety signals than other macronutrients. Could you briefly talk
about how macronutrients, including protein, but also
carbohydrates and fats, impact satiety. And from the
standpoint of somebody who, for instance, would
like to quote unquote, "lose a few pounds," right? Probably would be happy to gain
a little bit of lean body mass provided it was in a
particular location on their body, that
seems to be a thing now.

Directed hypertrophy,
if you will. And how much they should focus
on protein as a core component of creating this diet. Assuming everything else
is being done correctly. They're going to hit the
right number of calories relative to their
output NEAT, et cetera. How should we think about
protein and satiety signals? And are animal sources
of protein, indeed, more bioavailable? That's a tricky word. For sake of muscle
building, but also for sake of somebody who just
would like to lose body fat. They don't want to
lose muscle and they'd like to bring their
weight down a few pounds. LAYNE NORTON: So
a lot of things– ANDREW HUBERMAN: –or more. LAYNE NORTON: Yeah. A lot of things to unpack there. Of the macronutrients,
protein is definitely the biggest lever that you
can pull, because even if– it doesn't take a ton of protein
to get a lot of the muscle building benefits. I mean, I think
the benefits really start to plateau out around
1.6 grams per kilogram of body weight.

There's some evidence
that maybe even up to like 2.4 or
2.8 grams per kilo may give a little
bit more benefit. I think it probably
looks something like an asymptote
in terms of a curve where as you put
more into the system, you always get a
little bit more, but it just gets to the point
where it's so infinitesimally small benefit that it's for all
intensive purposes, no benefit. ANDREW HUBERMAN: But you
mentioned 1.6 grams of protein per kilogram of body
weight, would you consider that a threshold
that most people should try and achieve daily? LAYNE NORTON: I see very few
downsides to hitting that.

I mean, I know some
people– and this is going to get into a
separate conversation. But I know some
people will say, well, I don't want to stimulate
mTOR because that's going to make me die early. And I think, one of
the things to keep in mind is if you look at– there's kind of
this thought process out there that if
you're stimulating mTOR, that protein is going
to make you die early.

And first off, we have
very little human outcome data to support that claim. And the second thing
is, if you look at any macronutrient
isolation, I can make a mechanistic argument
that it's going to kill you. So fat– if you take
in fat and it decreases flow-mediated dilation. Flow-mediated dilation is
important for heart health in the short term. Carbohydrates stimulate insulin. Insulin, you know,
pro-inflammatory and all these other things. And so I can make an argument
for any single macronutrient to be negative for longevity. I really want people– this is something that
even scientists get wrong. They look at an acute
response of something and assume that is going to
relate to long term outcomes and signaling.

So let's just take
exercise, for example. If you didn't know
anything about exercise, and I said to you, Andrew,
I'm going to do something that's going to make you–
your heart rate go up, your blood pressure go up, your
inflammatory markers go up, your reactive oxygen species
increase, you're going to say– and it's going to damage your
muscles, you're going to say, I'm not doing that. That sounds horrible. But it does all those
things in the short term. But what is the long
term effect of exercise? You actually get healthier. All those things improve. Now, I'm not saying that
protein is a longevity hack or anything like that,
but what I'm saying is, I think some of
the arguments out there are based on mechanistic– this increases mTOR, therefore
we don't want to do it.

I think it is a much more
complicated argument than just that. So there's that. So protein is the biggest lever. I would shoot for 1.6
grams per kilogram. If you can do more, great. There doesn't seem to be
really downsides to it. Even up to very high
levels of protein. Jose Antonio did
a study, that was a year-long randomized
control trial. And again, it's just one year. But they were looking at all
sorts of different biomarkers. And basically, even up to like
4 grams per kilogram of protein, they couldn't really find
any negative health outcomes from it other than people were
just so satiated, they ended up eating less calories. So protein is a big
lever, because one, it has a higher thermic
effect of food, so you're getting a little
bit more calorie burn per day even though it's not
a ton because TEF is a pretty small percentage
of your overall energy expenditure.

But still a benefit. You're getting the
effects on lean body mass. If you're in a diet, it's going
to help preserve lean body mass, if you're at
maintenance, it's going to help build a
preserved lean body mass, and if you're in a
surplus, it's going to help build a
preserved lean body mass. Then you get the
effects on appetite.

So now, I want to be careful
because appetite effects tend to be very specific
to individual foods. So you can take a
high protein food and make it not very satiating. So take, for example, like
a really tasty protein bar, which back when we
were getting into this, no such thing existed. Now, you have protein bars that
actually take pretty darn good. But if you eat one of them, I
mean, are you really satiated? I don't really feel satiated,
that's my protein bar.

ANDREW HUBERMAN: That's
my premeal snack. LAYNE NORTON: Right. Right. So why? Because, I mean, it's
processed, refined, and made to be very palatable. But take something like a
200-gram chicken breast. Very satiating, right? And that's why when people
say, well, carbohydrates aren't very satiating, it
depends on the carbohydrate. I mean, when you look
at the satiety index, a plain baked potato is about
as satiating as it gets. ANDREW HUBERMAN: If I
eat a bowl of oatmeal, I feel pretty good afterward. LAYNE NORTON: Yeah. ANDREW HUBERMAN:
For a while, right? I mean, I usually– I'll eat that along
with some other things, but I completely agree.

So you're saying that the
form that it comes in, maybe, even how much chewing
is required, how good. It smells that your
psychological associations– because to me, a steak
is an incredible meal. I mean, if I had to pick
one food that I could eat, even though I'm
not pure carnivore, for the rest of my life, it
would be that because, I think, it would get me
where I need to go and then I'd probably
have to sneak some fiber.

LAYNE NORTON: Yeah. ANDREW HUBERMAN: But
it's an excellent point. I have a question that I don't
want to take us off track, but I'm hoping it relates enough
that you could answer it now. In the context of
this, if I'm going to eat let's say, 2 grams per
kilogram of body weight protein and I'm not eating
multiple meals, maybe I'm eating two
or three meals per day, I'm certainly going
to be eating more than the 30-gram threshold
that was thrown around for a long time that
we can only assimilate 30 grams of protein per meal.

Should I just not
worry about that? Some of it is going to go
towards the thermic effect of food, some of that
might be converted into glucose of all things
through gluconeogenesis. So should I worry about
this 30-gram cut off? Because I think balancing the
1.6 gram per kilogram body weight threshold
with number of meals, with the need to exercise
and work and live my life and sleep, et
cetera, pretty soon, you run into bottlenecks
where you just can't do it or you're spending so much
time trying to focus on it. LAYNE NORTON: You can't
optimize all the things at the same time. ANDREW HUBERMAN: You'd lose
your mind and your body. So what is necessary
in terms of frequency if one is getting
enough protein? And then tied into
that question, is there any
reality to this idea that if you eat one meal
per day or you're fasting and then you eat, let's
say, 200 grams of protein in a single feeding, that you
can assimilate more because you were protein starved.

Is that a real thing? LAYNE NORTON: So most of
the studies with protein are after a fast because to
assess it with stable isotope, you have to be in
a steady state. So we haven't observed that. It doesn't appear
that fasting really allows you to assimilate
more protein after a fast. So this gets into a core
of one of the things I looked at in my
PhD, which is, does protein distribution matter? Because most Americans get about
65% to 70% of their protein at dinner. Breakfast tends to be pretty
minimal protein foods. ANDREW HUBERMAN: Do
any cultures, actually, eat big breakfast and not
a big lunch and dinner? We all heard that was ideal. We'll get into circadian
timing in a little bit, but does anyone
actually do that? Steak and eggs for
breakfast and then taper off the rest of the day? LAYNE NORTON: I
know German culture tends to have a big
breakfast, but also tends to be like sugary
foods and whatnot. As far as like teleological, I'm
actually not sure about that. So if you look at
that, and then you consider that protein
doesn't really have a storage mechanism.

People will say, well, lean
tissue is a storage mechanism. That's like saying a house is
a storage facility for wood. Yeah, if the house
is made out of wood you could get wood out of it,
but that's not why you build. You're building the
house out of a demand. Same thing for muscle tissue. There is a free
pool of amino acids, but it's very, very small. So when you consider things
like fat, which, basically, has unlimited storage capacity,
carbohydrate, at relatively large storage
capacity, you can store 400 or 500 grams of carbohydrate
between your liver and muscles. And then protein, which almost
has no storage capacity, the idea that, OK,
you could make up for a low protein at one
meal by over consuming another meal didn't
make sense to me.

So one of the studies we did– and again, in rats, we took– both groups were getting whey
protein, so a high quality protein, they were getting
the exact same amount of calories, exact same amount
of nitrogen, exact same macros. Everything was the same. The only difference was,
one group, basically, got three meals of similar
amounts of protein. Dinner was a little
bit bigger, because we wanted to keep it somewhat
similar to how people eat. But each meal was going to be
over the threshold to stimulate muscle protein synthesis. Whereas the other
group, I constructed it so the first two
meals of the day should not stimulate
muscle protein synthesis. It should be under
that threshold. And then the last
meal was about 70% of their total daily protein. And so we had them eat
those for 11 weeks. And I'll never forget this.

This is how obsessive
I became about it is, there were 110
animals in the study, and I made all the
diets and I weighed out exactly every single meal
for every single animal for 11 weeks. So I was in there at 6:00
AM, I was in there at noon, and I was in there at 6:00 PM. ANDREW HUBERMAN: I love it.

That's kind of PhD student
that professors dream of. You're sounding a dream student. LAYNE NORTON: So at
the end of 11 weeks, we looked at like lean body
mass, we looked at body fat, we looked at hind limb weights. We didn't really see
differences in lean body mass, but what we did see
was a difference in hind limb weights. It wasn't massive, but there
was a significant difference in the size of the
muscles of the hind limbs of these animals. And so it's interesting
that there wasn't a difference in lean body mass. And what we found, at least
with the liver, the animals that we're eating one meal
with really high protein, actually had bigger livers,
not like a huge amount and not something that I
would consider unsafe, but it was a statistically
significant difference. And so to me, at
least, like I'm trying to explain like no
difference in lean body mass, but a difference in
these hind limb weights, maybe there's some
sequestering of– that's fueling a little
bit more protein synthesis of the splenic
tissues rather than– because you're capping out
skeletal muscle protein synthesis.

And we do know that the
splanchnic tissues are more sensitive or
have a greater rate of protein synthesis per day. Like, the rate of skeletal
muscle protein synthesis in humans is about
like 1% per day. So it takes like 100 days to
turn over skeletal muscle. Whereas like your entire
gut, your entire GI will turn itself over in
like two to three days. So really– and the liver
also has a very high amount of protein synthesis, which
is one of the reasons. It's actually one of the most
metabolically active organs. So all that to say, it has not– there's been one human study
that showed something similar. And then there's been a
couple of others that didn't. And then in the intermittent
fasting studies, which is maybe a good tool to look at
compared to continuous feeding, one thing I will say is
it looks like the 16/8 intermittent fasting style.

There's been a couple of
studies with Grant Tinsley. And this is something I've
changed my mind on as well. Grant Tinsley has done
a couple of studies where they did use
the 16/8 protocol. They had them train during
their feeding window, and they had them eat– I think it was at least three
protein-containing meals during those eight hours. ANDREW HUBERMAN:
These are humans? LAYNE NORTON: These are humans. And they saw no difference
in lean body mass at the end of the study
compared to people who were eating as many times as
they wanted throughout the day. Now, if you look at some of the
more extreme forms of fasting, like alternate day fasting
or like 20/2 or 20/4, there are some studies where
you do start to see differences in lean body mass. So my suspicion is,
and I'm just guessing.

So this is tenuous. My suspicion is,
probably if you're getting like two to three high
quality protein meals in a day, you're getting the vast majority
of the benefits of protein. The most important thing
is getting enough total. And then secondarily,
trying to get at least two or three meals with
high quality protein in. But if you're going pretty
extreme with like alternate day fasting or maybe
only one meal a day, then I think there may be some
effects on lean body mass. But again, these can be
mitigated as well if you're doing hard resistance training.

Typically, that is
the biggest lever in terms of lean body mass. Yes, protein distribution
may make a difference, but I'm trying to put
it in context so people don't feel like they need to go
out and eat four meals a day. But again, so what I would say
is like some of the more milder forms of time-restricted
eating appear to be fine for lean
body mass, now, the caveat is the following. One of the nice things
about animal studies is when you
consider– if you want to have a high subject
number, high level of control in a long duration, it's
pretty much your only option. So in our research
review reps, I created a Venn diagram,
which basically is like three circles
crossing over. One is study duration,
one is level of control, and the other one
is subject number.

And to get all three of
those circles to cross over, it almost has to be an animal's. ANDREW HUBERMAN: Right. And REPS, it's a
newsletter or a book? LAYNE NORTON: So it's our
monthly research review. So every month we review like
five studies that come out in fitness and nutrition. We'll usually do at least
one nutrition, one training, and one supplement per month. ANDREW HUBERMAN:
We will put a link to where people can sign up. This is a sign up format? Great. LAYNE NORTON: Yeah. So it's a
subscription-based service. So basically, when– people
might look at my study, well, why did you see difference
in muscle weights whereas some of these other
studies don't see a difference? I weighed out every
single meal for 11 weeks, and keep in mind that 11
weeks in a rodent's lifespan is a really long time. That's about an 1/8 of
their total lifespan. So is it that there's
no effect or is it that the effect is
relatively small and would take a really long
time and very high level of control to see in humans? I don't know.

But I think what I would say
relatively confidently is if you're going to do like
a 16/8 intermittent fasting, you're probably fine. Especially– and again,
what is the goal? Like if you're a
bodybuilder looking to be the most massive
person you possibly can or you're a football
player or you're in some field that having as
much lean body mass as possible is really important for
you, then I would say, well, you're not really
gaining a whole lot by doing some form of
time-restricted eating.

ANDREW HUBERMAN: I think most
of the people listening to this do not fall into that category. LAYNE NORTON: Right. ANDREW HUBERMAN: I think most
people want to maintain or lose weight. They'd like to,
perhaps, add a bit of, quote unquote, shape or muscle
to specific areas of their body and lose body fat. LAYNE NORTON: Right. And I think your normal
forms of time-restricted, and you're probably
perfectly fine for that. And again, I don't want
somebody to think, well, I do alternate day
fasting, there's no point to me resisting
training because I'm going to lose muscle mass.

No. No, no, no, no. You can still build
muscle doing that. You just might not
build as much muscle as you would if you were eating
in a more traditional format. But if that's something that
works for you and your goals, and especially, if it's fat loss
or controlling your calories, then again, it's about the
hierarchy of what's important.

So to answer your question, I do
think that timing and frequency matters a little–
not so much frequency, but distribution more so. So I think the
distribution matters, but it's a much smaller
lever than just getting enough total protein in. And then as far as
animal versus plant, I used to be in the
camp of, there's no way somebody can
build as much muscle on a plant-based diet. And now, I think I've
come back to, you can, it just requires a
little bit more planning. And I don't want to say
always, but it's very difficult to do without an isolated
source of protein. So unless you're going to
supplement with an isolated plant source of protein,
it's very difficult to get enough without going
over on total calories because you can figure
that, especially, like take somebody who may
be calorically restricted, trying to get enough protein
from whole intact plant sources. So you've got a few different
things working against you. One, the sources of protein
you're consuming also have carbohydrate and/or fat. Two, it's a less bioavailable
form of protein, and three, it's a lower quality of protein
in terms of it has, typically, less leucine, less
branched amino acids, and less essential amino acids.

ANDREW HUBERMAN: You answer
the question that I almost interrupted you
to ask, which was, does it boil down to
the leucine content? And it sounds like that
is one of the components. And that a lot of the
vegan and vegetarian sources of excellent protein,
that excellent protein vegetarian or vegan source
is co-packaged with calories from carbohydrates
and/or fat that make it hard to stay under
the caloric threshold. Whereas a steak is– I'm not– and
obviously, people might want to avoid that
for ethical reasons.

LAYNE NORTON: Sure. ANDREW HUBERMAN: But that's
a different matter entirely. But a steak or a piece of
chicken or an egg is– well, an egg has a yolk which
is, there's fat there. But is almost a pure
protein, fat source. There's no carbohydrate
along for the ride. LAYNE NORTON: Right. So I think what I would
say is that, you can do it. Takes a little more planning. And you're almost always– if
you're a vegan, especially, you're going to be
better off like something with some isolated form
of protein or vegan form of protein. Now, this word gets
into people say, well, what about the
limiting amino acids and those sorts of things? It's a consideration. Some of the better
forms of vegan protein in terms of amino acid
content are like soy. Now, I hear everybody
screaming online about their testosterone levels. In terms of actual outcomes
and looking at testosterone, there was a recent meta
analysis looking at soy.

And I think if it's your
only source of protein, then maybe the
dosage is high enough to cause some weird effects. But if you're just using it
like once or twice a day, it doesn't seem to have
an effect on testosterone or estrogen. So that can be
a decent source of protein, because it is a
complete protein source. It does have a PD cause of one,
which PD cause is basically a measure of protein
quality based on, does it provide enough
of all the amino acids so that none are limiting? And so soy is one of the only
vegan sources that does that.

Interestingly, potato
protein isolate actually has a similar essential
amino acid content to whey. So isolated potato protein. It's just really hard to find. ANDREW HUBERMAN: Interesting. LAYNE NORTON: I've
been trying to source– ANDREW HUBERMAN: But
vegans take note, vegetarians take note, because– or vegans rather, because
whey is vegetarian, and whey is a very high
quality protein as far as– LAYNE NORTON: Very
high quality proteins. And actually– they're actually
creating whey now out of– I think it's– I may mischaracterize this. But I believe they're able to
produce it out of like yeast or something like that.

ANDREW HUBERMAN: Amazing. LAYNE NORTON: That–
so for vegans, now, this is a great
option because you can have whey that's
not animal-based that is going to be every bit
as good as an animal-based whey. So I think that's great. Getting to the leucine– let me go back, sorry. So another reason that using an
isolated protein can be helpful is because it's
more bioavailable as well when it's
been isolated out. When the protein bound up in
the actual plant material, it tends to be
less bioavailable. Now, cooking can help
increase the bioavailability because it breaks some of
those bonds and whatnot. But it still seems to be lower. And you don't– it's
really interesting. There was a recent study where
they did a corn, wheat, and pea blend of protein versus whey. And basically, the
outcome was, 30 grams of each stimulated protein
synthesis to a similar degree.

But the plasma amino acids
in the plant-based protein still did not get as
high as with whey. Now, it may be that that's
just– it doesn't matter because once you get
to a certain level, you get all the benefits. But I still found it
interesting nonetheless that they didn't
quite get as high. The other thing to consider with
the vegan sources of protein is the leucine content. So one of the studies
we did was we looked at wheat, soy, egg, and whey. Isonitrogenous,
meaning we equated protein between the
groups, isocaloric, we equated calories.

And we looked at muscle
protein synthesis. And I think this was– the
meals were 15% of total energy from protein. So like your food guide
pyramid level of protein. And we saw that in the
wheat and soy group, they did not increase
muscle protein synthesis, but the egg and whey group
increased muscle protein synthesis. Now, what's really
interesting is we went back and we took wheat and added
free leucine to it to match the leucine content of whey and
the protein synthetic response was identical.

So again, I don't like to
simplify things too much, but leucine appears to
really be driving this ship. And I'll never forget, Layman
called me into his office one day, and he would always do
these thought experiments of– he liked to think
about why something occurs the way it does. ANDREW HUBERMAN:
Dangerous territory. LAYNE NORTON: Yeah. So he would say– one day, I'll never
forget, he said, Layne, why do you think the body
evolved to just sense leucine for muscle protein synthesis? And of course, I'm
like, I don't know, man. I just work here like. I'm just trying to get my PhD. And he said, well,
think about it. You would want something that
really wasn't extensively metabolized by
the gut and liver, because you would want to
show up in the blood in values that reflect what you just ate. Makes sense. And you would want it to
have passive diffusion across the muscle
cell because you want to be
concentration-dependent, which it is. So– ANDREW HUBERMAN: Get into
the tissues and cells that need it most.

LAYNE NORTON: Right. So not having active transport,
but rather passive transport. So yeah, I thought that
was really interesting the way he broke that down. So few different options for
the vegan folks out there. You can use an isolated
source of protein. And again, like there's going
to be good options coming, because this plant-based
whey is going to be a great option for folks. You can add free leucine
to it, to whatever your source of protein is.

ANDREW HUBERMAN: Just by
supplemented leucine powder. LAYNE NORTON: Now,
it tastes horrible. ANDREW HUBERMAN: Yeah. I think I've heard that. Maybe I've even tried it. LAYNE NORTON: It's completely
non-polar, it does not not dissolve in anything
And it is gross. ANDREW HUBERMAN: Can it
be put into capsules? LAYNE NORTON: It can
be put in the capsules. Yeah. So you could take a capsule. Like for example, if you're
eating your normal meal, you could just take a capsule
of like 1 gram of leucine. Is probably going to bump
you up enough that you're going to be good to go. And then there's
options like blends– especially, with corn. Corn is actually
very high in leucine. That's a percentage
of its protein. Now, you've got to remember
like, you go eat corn on the cob and you're getting
like 2 grams of total protein. So it's not that much leucine. But if you isolate out the
protein, put it into a powder, well, now, when you're getting
like 80%, 90% of the weight is now protein, corn
is actually about 12% leucine in terms of the protein.

So a great source of leucine, it
is like almost frank deficient in some other amino acids. But you can blend it with a
few other sources of protein. Like you could blend
it with a soy, a pea, and you can create these
complementary blends that would actually have
quite a bit of leucine, but also some of the other
essential amino acids. So there are options out
there for plant-based folks. And I mean, we have
seen people who are plant-based build
impressive amounts of muscle. There's quite a few bodybuilders
that are plant-based.

ANDREW HUBERMAN: And a lot of
the endurance athletes like it. And even though– when
we talk about muscle, we think about muscle
building often. Performance in endurance sports. And also just performance
for the typical person who's doing some
cardiovascular training, hopefully, some
resistance training. Also and just living life. I mean, many more
people now, it seems are vegan or at least avoiding
meat, in particular red meat. I'm not one of those people. I limit the amount,
and I certainly focus on the quality
of what I eat. But I do eat red
meat, which brings me to a question about just
generally in terms of food choice, can we come up with
a relatively short summary of the following? Tell me if this
is correct or not. That most of us
should be focused on– for sake of health
span and lifespan, should be focused on ingesting
minimally non-processed and minimally processed foods.

Maybe even cooking our own food. I realize that's heresy now. But ideally, we would
do some of that. And really trying to avoid
foods that are highly processed and have lots of sugar. And I'm using this as a
segue to get into a question that I really want
your answer to. I've been dying to ask you this,
which is if sugar intake is not actually going up as much as
people think it is, why are people getting so much fatter? So what do you think about
just a general statement that we should try and eat
foods that are low to no– minimally to not processed
for about 80% of our foods.

Is that a reasonable number? LAYNE NORTON: Yeah. It's hard to actually get
completely unprocessed food because almost everything
goes through some form of processing. ANDREW HUBERMAN: So I'm
thinking like anything that wouldn't survive long
without refrigeration– LAYNE NORTON: On shelf? ANDREW HUBERMAN: Yeah. On a shelf, like an
apple or a banana. So like oatmeal, like
ground oats to me as long as there isn't
a bunch of other stuff and they would be
minimally processed.

A steak is not really
processed, although it's cut off the animal, et cetera. So there's a few steps in there. But that's what I mean. LAYNE NORTON: Yeah. ANDREW HUBERMAN: Yeah. LAYNE NORTON: And I think
everybody gets the gist. I'm probably a
little bit pedantic when it comes to this stuff. ANDREW HUBERMAN:
No, this is good. Actually, one of the
things I appreciate about you is something that
I get teased a lot by people close to me, which is the
caveats and the insistence on precision is really
important because especially with online
communications these days, it's like a runaway train. People will– LAYNE NORTON: It's too
easy to misinterpret what you're saying. ANDREW HUBERMAN: It's very
easy to misinterpret it. And the misinterpretations
are often used to leverage whole new ideas
about what is and isn't true. Mostly about what is true. So I really
appreciate the nuance. And this is what a longform
podcast really allows us to do, is catch every curve, you know? LAYNE NORTON: So I would 100%
agree with what you said.

That if you were going to
make a broad stroke, that trying to focus on
minimally processed foods is very important. The one caveat I would
say is, I think it's important to understand why. Because otherwise, people can
make this weird association that, if I eat any minimally–
or any processed food, it's going to kill me. Or like every time
I eat it, it's like I'm smoking a
cigarette and my health– my longevity is declining. Based on the studies we have,
it's mostly about the energy. That processed food just gets
people to spontaneously eat more. And Kevin Hall showed this
in his study that was very– I mean, he designed some
of the most elegant studies in nutrition. ANDREW HUBERMAN: He's great. LAYNE NORTON: And they,
basically, took people from a minimally
processed food diet, and then gave them access
to ultra processed foods. Very few instructions. Just eat to you feel satisfied. And they spontaneously
increased their calorie intake by 500 calories a day. I mean, that's massive. And we haven't quite
figured it out. People say, well, it's sugar. It doesn't appear to be sugar
in terms of just an isolation.

Well, it's fats. Doesn't appear to be
fats in isolation. Well, it's the combination
of sugar and fat. Partly, well, it's
the combination of sugar, fat and salt. Partly. But there's some
kind of overall magic to the texture and
the mouthfeel and just the overall
palatability of stuff. Which is always
why I say, there's like right and wrong ways
to these different diets. Like, for example, like there's
the right way to do plant-based and then there's like what's
in some of these documentaries where they're eating like
plant-based mac and cheese. And again, I love a
good mac and cheese, but that should not form– that should not be
pitched as a healthy diet.

Just because it's "plant-based." Because I mean, you're eating
a highly processed food that's very palatable
and easy to overeat. Same thing for keto. You've now got like
keto ice creams and you've got keto cookies
and all these sorts of things. And I'm like, yeah, and
if you look at them, they actually have more
calories than the normal stuff. And I'm like, yeah,
this is completely missing the point here. Like you're actually
just taking yourself– the whole point of those
diets is the reason you tend to lose
weight is originally like good luck 10
years ago, doing a keto diet, eating processed food. Like you just couldn't
do it, really. Now, you can. But the problem
is, it's not going to work because you're
going to be still consuming too many calories, because
even though it's keto, what are they doing? Well, they're trying to
make it more palatable, they're trying to make
it better mouthfeel, which, I guess, if you're being
keto for the sake of being keto, great, but if you have
hopes of body composition modification, it's going to
really negatively impact.

So yes, I think minimizing
the amount of processed foods you consume can be important. Now that being said, it
depends on the individual and their goals. If your goal is to, for example,
build muscle or maintain a high body weight for a
sport, for example, like an NFL offensive lineman
or something of that nature, or if you're– I worked with an NBA
team, they were kind of– I can't disclose anything,
but they were looking at drafting a certain player. And like for them, processed
foods may actually be a tool. ANDREW HUBERMAN: Or a teenagers. We all want young people to
eat more healthily, I think. Develop great habits. But some of them, their
caloric needs are so high– LAYNE NORTON: So high.

ANDREW HUBERMAN: –that if
they were eating what I eat, they're going to dissolve into– they'll just waste away. LAYNE NORTON: So I
describe this, again, with a financial example. It's like a budget. So if I make a million
dollars a year, for example, is it OK for me to
buy like a $100,000 sports car? Let's assume that
loans don't exist. Is it OK for me to buy
a $100,000 sports car if I still am able to pay my
mortgage and pay my utilities and take care of my
responsibilities– the things I should do.

Is OK if I do that if it makes
me feel good and it's fun? ANDREW HUBERMAN: OK by me. LAYNE NORTON: Yeah. It's fun. Like it fits in your budget. If I make 50 grand
a year, should I be going out and
buying a sports car? Probably not,
because I'm not going to be able to pay
my mortgage and all these other responsibilities. So your protein, your,
fiber your micronutrients. These are your responsibilities. But those become
much easier to hit when you have higher calories. So if you're eating
4,000 calories a day for whatever goal you
have, you're probably going to have some left
over and like good luck eating 4,000 calories from
minimally processed foods, quite frankly,
you'll be miserable because you're going
to have such gut feel that you're going to feel
like you can't even move.

And so again, now,
it becomes OK, well, is there something
inherent to that food processing? Is there something
that we can pick out that we know, OK,
well, this is going to be a negative
effect on health, even like body
composition stuff aside. And I would say,
there's not really great evidence of that so far. And a great example
of that is sugar. I mean, I actually just
wrote a really long article on my website about why I
think sugar was not the root cause of the obesity epidemic. And you mentioned sugar
intake in the last 20 years has actually gone
down a little bit. ANDREW HUBERMAN: Alcohol intake,
well, if you look on the whole it, might have gone
up a little bit, but certain certainly
in the male sector, it's gone way down drinking. Used to be– there
was a 5 o'clock. People were drinking all day.

People are smoking a lot less. I think it's a real puzzle. I'd love to know what
your hypotheses are. LAYNE NORTON: Well,
smoking could actually be in opposition because
nicotine is actually an appetite suppressant. ANDREW HUBERMAN: Appetite
suppressant and also increases focus. The problem is it often
arrives in a delivery device that can kill you. LAYNE NORTON: Yeah. ANDREW HUBERMAN: But nicotine
itself is a powerful agent. It also can offset age-related
cognitive decline not entirely, but it makes the
brain work better. LAYNE NORTON: I've got a buddy
who doesn't like caffeine. And he just takes those
nicotine pouches and, basically, has one in almost
all day because he's like– he has a very stressful
job and he's a high performer.

ANDREW HUBERMAN: Yeah. You have to be careful
how you deliver it, but there's a Nobel Prize
winning neuroscientist that will chew five or six
pieces of Nicorette an hour, which I do not recommend,
but when he quit smoking, he just simply couldn't
function as well. And he was the
one who pointed me to do the literature
on offsetting age-related cognitive decline. Even neuron maintenance,
and it's pretty interesting. LAYNE NORTON: Well, it's a
pretty impressive nootropic to be honest.

Now, the first
thing to realize is when we're talking
about consumption data, this is based on actual
production, basically. They're assuming that,
OK, we're producing this amount of
these foods, so we can assume the consumption
is going to follow that. So it's not a
direct measurement. But it has been validated
in a few different studies. We know that oil
consumption has gone up. Like that that's, yeah. That's one of the big ones. And this forms the
crux of– like, the seed oils are
like the root of– ANDREW HUBERMAN: It's
definitely the question that I'm going to ping you on.

LAYNE NORTON: They're going
to come into your house and kick your dog and punch your
mom, and all kinds of stuff. And I'm happy to address those. So calories have still gone up. There's some people
who claim that they've gone– they've plateaued. I think the data seems to
suggest that calorie intake is still increasing. And the other thing
to keep in mind is, even if it's
plateaued, it's still at a high enough level
that obesity is probably going to continue to
increase up to a point where it'll probably plateau
if calories have plateaued. ANDREW HUBERMAN: What
about energy output? Leaving aside NEAT, because
that sounds highly individual, I mean, people are– the people we know are
focusing on exercise.

But there are a lot of folks
out there that don't exercise. LAYNE NORTON: And energy output
has gone down over the years. I mean, it's very
obvious when you look at how people
work now compared to even 30, 40 years ago. It's much different. ANDREW HUBERMAN: Less walking. Also, I learned recently
that kids in high school don't take PE class
in many schools.

But we had to suit up
and run and suit up. And if you didn't bring
your change of clothes or you didn't wash them in
which case you'd be better off just not wearing them, nothing
like the smell of a boys locker room after a weekend,
I can still remember it and it's not pleasant. But you had to run and do your
pushups with everybody else or play volleyball in your
regular school day clothes. So my understanding is that,
physical education is not part of the basic
education any longer. LAYNE NORTON: It probably
depends on the state, but I know many states have
done away with it just because of budget cuts. ANDREW HUBERMAN: So
activity is going down, caloric intake is going up. Maybe– LAYNE NORTON: Plateauing
a little bit, yeah. ANDREW HUBERMAN:
–maybe plateauing. Is that sufficient to
explain the obesity epidemic? LAYNE NORTON: Based
on what I've seen, I think it's pretty sufficient.

ANDREW HUBERMAN: So it
might not be that big of a mystery after all? LAYNE NORTON: No, I don't
think it's a big mystery. I think that people don't like
the concept of energy balance, and I think because
they insert judgment into it, which is, OK, if
you're gaining weight over time, at a fundamental level,
it means you are eating– you're consuming more energy
than you're expending. People insert the judgment,
which is, you're lazy, you're a sloth,
or whatever it is. And I think there's a
lot of people out there who actually think
that, I actually remember talking to
somebody who was like, well, I would never hire an
obese person for a job because it's just obvious
that they're lazy. And I just remember
going, are you serious? Like, there are
plenty of very, very smart high-achieving
people who are obese. And like it's not– this is what happens when you
just put people in buckets. People are much more
complicated than this. Yes. There is some personal
responsibility. But then when you look through
the data and you take– there was a study
done in obese women where they found that
women who were obese were 50% more likely to have
had some form of sexual assault trauma in their past.

We know that people
from lower income areas are more prone to be obese. There's several people who have
a higher ACE score, I believe, which of measures like
traumatic childhood events. I believe, there was a
study showing they're more likely to be obese. So there's– yes, it is an
energy imbalance problem, but just saying,
eat less, move more, that's like telling
broke people, well, just earn more money
than you spend. It's technically right,
but it's very unhelpful. What is more helpful is
to describe and implement the habits and
behaviors that will allow them to achieve that. So I realized we go
off track a little bit, but circling back to
sugar, circa 2005, I believe that sugar
was fattening and bad for your health independent
of any other variable. So independent risk factor. And again, I want to be very
clear about what independent means. Independent means independent
of all of the variables. This thing is bad for your
health and body composition. ANDREW HUBERMAN: So on its own,
independent of whether or not, for instance, it increases
hunger and appetite.

LAYNE NORTON: Right. Or caloric intake. I was at a graduate
school mixer. And one of the
professors there was somebody who had done
research on high fructose corn syrup and fructose,
specifically, as well. And he was talking
to another professor and he had done this study in
rodents where he had fed like– I think it was like 60%
or 70% of their calories from fructose. And they saw some
really weird things happen in the liver
with lipogenesis and all this kind of stuff. And the other professor
is saying to him, yeah, it's pretty obvious
that high fructose corn syrup is fattening. And this professor who
had done this research said, yeah, because
it's people overeat.

And he's like, don't
you think there's something inherent to it? And he said, no, I think
it's just calories. People are eating
too many calories. He's like, we did a proof of
concept looking at could we– like, try eating 70% of your
daily calories from fructose. You actually can't do it. High fructose, corn syrup
is only 55% fructose.

So if you ate nothing but
high fructose, corn syrup, you would still not
get to this level that they fed in this study. So that got me kind of
like questioning my beliefs about it. So then I went through and I
said, OK, look, let's take out the epidemiology. Not that epidemiology
is useless, but people who eat
more sugar are also likely to eat more calories. So then I looked for the
randomized controlled trials where they match calories
and vary the amount of sugar. And it doesn't seem
to make a difference. At least from fat
loss or fat gain– ANDREW HUBERMAN: But
what about health? So for instance, if somebody– and I know somebody like this
who loves sweets, is thin, get some exercise, not a ton. But my concern is that,
a significant fraction of their calories are coming
from these sugary foods and therefore they're not
getting enough fiber– maybe protein, et cetera. LAYNE NORTON: So let's look
at epidemiology for a second, then I'll address
this more directly. When we look at
epidemiology, people who eat higher amounts of
sugar tend to be more obese, they tend to have worse
biomarkers of health.

The people who eat fruit–
a lot of fruit sugar, don't have those
same associations. So why is that? Well, because fruit
has fiber with it. So I started to believe,
based on the data I was looking at, that
high sugar intake was not the problem per se. The problem was that high
sugary foods, typically, are very low in fiber. But if you're getting enough
fiber, is sugar a problem? So there was a classic
study by Surwit in 1997. I think it's still
the best studies of this day looking at this. And I know those people who
say, well, it was done in 1997. It has no relevance. You know, I know, if it's a
good study, it's a good study. ANDREW HUBERMAN: Some
studies are timeless. In fact, they have
greater relevance– LAYNE NORTON: You're not
going to go back and undo the discovery of DNA
because it was 60 years ago or whatever it is.

ANDREW HUBERMAN: No. LAYNE NORTON: So they looked
at an 1,100-calorie diet, so low calorie diet. One group was eating over
110 grams of sugar a day, like sucrose. The other group was eating
about 10 grams of sugar per day. Calories, protein,
carbs, fats all matched. And they provided all the
meals to these participants. So very tightly controlled. And it was over six weeks. Both groups lost the exact
same amount of body fat. So it doesn't seem to matter
for body composition in terms of sugar per se. Then they also looked at
some biomarkers of health like blood lipids and blood
sugar and some other things.

Again, there was no
real differences. The only difference was– so all their biomarkers
improved in both groups. The only real difference was
a small difference in LDL. So the group eating low sugar
had a better improvement slightly in LDL. But that's probably because
they were eating more fiber. And we know fiber can bind
to cholesterol and lower LDL cholesterol. So now, I want to caveat this. Sugar probably doesn't have
any positive health effects. So there's that. And nutrition is an exchange. If you're eating one
thing, you're not eating another thing, right? So but what I would
tell people is, focus probably less on
sugar, focus more on fiber. So if you're eating 30, 40,
50, 60 grams of fiber a day, but your sugar is,
80, 90 grams, I would not be that
worried about it, especially, if you're
controlling calories as well. What I would be worried
about is if you're eating just a decent
amount of calories and not getting enough
fiber and in general, right? And even in studies,
there's a few meta analyzes out now looking
at isoenergetic exchange of different carbohydrates
with sugar carbohydrates.

So fructose and
glucose and sucrose. Now, why is this important? Well, again, if
you're not equate– when I say isoenergetic,
that means equal in energy, equal in calories. So basically, when they exchange
either sucrose or glucose or fructose for other
forms of carbohydrate, do they see differences in
these markers of health? Like HbA1c, fasting blood
glucose, blood lipids, with rare exceptions, and I
can't remember all the data points exactly. But the take home
is, doesn't really seem to make a difference? Now, for anybody out there,
straw man is my argument, I am not advocating
for sugar consumption. But I think it's
important for people to not create weird
associations in their minds because one of the things
I've observed, especially, in the fitness industry,
is when people feel like they can't eat something– it's one thing if you say, I
am choosing not to eat this just because I'm choosing to. But it's a very different
thing when you're purposely restricting because you
feel like something is bad.

And this– I mean, you
know the human brain is, in many ways, amazing and
in many ways, really dumb. So when you purposely try
to restrict something, what tends to happen is you're
more prone to binge on it. So people who will
try to– well, I'm never going to eat
you know sugar again or I'm going to try
and limit sugar. And this isn't the
case for everybody. But they have actually
shown now in studies, people who are purposely restricting
a specific nutrient, they tend to crave
more of that nutrient. And if they do get exposed to
it, they're more likely to have what's called a disinhibition
reflex, which is basically a binge response. Because the thinking
goes, well, this is bad, and there's no context on
dosage making the poison.

This is just bad in general. So if I have it, I've
already screwed up. I might as well just
have as much as I want. And I like Spencer Nadolsky's
comparison to this. That's like getting a flat and
then going out and slashing your other three tires
because you might as well. So I really– I try to come from that
perspective of, I've seen so many people
struggle with, maybe, not an eating disorder, but
disordered eating patterns because of these associations
they've made in their mind. And so that's why I'm so
pedantic and a stickler about saying, OK,
yes, it's a good idea to eat mentally
processed food and try to avoid processed foods.

But not because processed
foods are bad per se, but what the outcome tends to
be from a lot of processed food consumption, which is
overconsuming calories and then therefore energy toxicity
negatively contributing to your health. ANDREW HUBERMAN: Yeah. It seems like it, again,
returns to the potential for a positive, negative, or
neutral behavioral change. And perceptual change
of like craving of food all the time that you
can have is terrible. That's a terrible
state to be in. And this, I think, is a
perfect segue way for something that first brought
us together, which was this thing about
artificial sweeteners. And let me just, for the
record, be very clear. I have long ingested foods
with artificial sweeteners. So throughout graduate school,
I didn't have the best habits. They're healthier now
than they were back then.

But I would drink a Diet
Coke or two per day. I still have the
occasional Diet Coke, I'm not completely
averse to drink something that has artificial sweetener. Although, I do avoid
sucralose for reasons that maybe I can get
into a little bit later. But a lot of the
things I consume contain stevia, which
is not artificial but it is a plant-based
non-caloric– or low caloric sweetener. And I don't have a
problem with that. I became very interested in
artificial sweeteners because of the animal data
pointing to the idea that they may disrupt
the gut microbiome, and then disrupt the gut
microbiome, as you pointed out, is a very broad statement. We don't really
know the percentage of lactobacillus, exobacilius,
or whatever ilius in there– they all seem to end in ilius– is ideal. And in fact, a lot
of these companies that are having people
send in their stool samples for analysis of the microbiome. I mean, take note,
we don't really know what a healthy
microbiome looks like, but we know what an unhealthy
microbiome might look like.

And it's one that doesn't have
a lot of diversity in there. So I was interested
in that, then there's the recent human study
which we should definitely get into. But I was mostly interested
in artificial sweeteners for the reason that there is
this food conditioning effect. And you see it in
animals and you see it in humans that if you ingest– well, coffee is a
really good example.

Coffee doesn't actually
taste good folks, even though I like it. But when you taste coffee
for the first time, most people think it's
bitter and disgusting. Most, everybody,
like 95% of people say, this doesn't taste good. LAYNE NORTON: Wine,
beer are same thing. ANDREW HUBERMAN: Yeah. But people have learned to
associate the state of being caffeinated, which most
people like in order to just feel normal,
right, caffeine is one of the few drugs we
ingest just to feel ourselves enough that soon– myself included,
really look forward to and enjoy a cup of coffee. So it's a powerful
example, in my opinion, of the food conditioning effect. So it's like a Pavlovian thing. Instead of
salivating, you crave. LAYNE NORTON: Right.

ANDREW HUBERMAN: And it did
seem that this study from Dana Small's lab, which admittedly
was a small no pun intended study itself, not
very many subjects, showed that if you ingested
artificial sweeteners along with food that contained
glucose, that you could maybe even get a heightened
glucose response just from the artificial
sweeteners after a while. You and I connected over
this study on social media. You pointed out that the
design, the study wasn't superb. There was co-consumption
of glucose, which made it complicated. We can go into that. But the reason I'm spouting
off all this context is, artificial sweeteners
are many things. So I'd like to talk
about their effects on blood sugar in
the acute sense and according to what we
might ingest them with and how they might be
changing blood sugar regulation at the level
of brain and/or body.

And then the gut
microbiome data, I think, are interesting
enough to discuss. And I have changed my view
on artificial sweeteners based on what you've taught me. So this is a case
where I've completely changed my view,
which is that, now, I don't have any problem
with them whatsoever based on the current data, which is
not to say that I'm gulping down cup fulls of sucralose,
but I feel OK ingesting some stevia and some aspartame
and I'm not too worried about it. LAYNE NORTON: Yeah. So I think stepping
back from a broad view, we have to think about, again,
the hierarchy of importance. And what are you replacing with? So there is no situation
where it is not a net positive to take somebody who drinks
sugar sweetened beverages and have them drink
an artificially sweetened beverage.

In the meta analysis, there was
actually a recent network meta analysis looking at markers
of adiposity, HbA1c, a bunch of different
health markers, and when you substitute,
we'll call it non-nutritive sweeteners,
and stevia is not artificial. But so when you substitute
NNS for the sugar-sweetened beverages, you see improvements
in a lot of different things. What was really interesting
about this network meta analysis was they also
looked at water substitution in place of
sugar-sweetened beverages. And the effect wasn't
as powerful as– and these are randomized
controlled trials.

ANDREW HUBERMAN: So artificial
sweetener containing beverages are more beneficial– LAYNE NORTON: Were
better for adiposity– for improving adiposity, and
then in the health markers, it was kind of a wash. Water and non-nutritive
sweetener, beverages performed similar. But there were better than
sugar-sweetened beverages, obviously. So they then based on– a network meta
analysis is where you can compare to things that
didn't get compared directly. So there's not many studies
comparing NNS versus water directly.

But if you have a
common comparator, so if you compare A to B
and B gets compared to C, you compare A to C based on
how they interacted with B. Butchering it a
little, bit but that's the crux of a network
meta analysis. So they looked at
NNS versus water and found that actually,
in NNS was slightly better for improving adiposity. ANDREW HUBERMAN: NNS, of course,
being non-nutritive sweeteners. LAYNE NORTON: Right. ANDREW HUBERMAN: Yeah. LAYNE NORTON: So now, again,
if you like drinking water and you don't want to– I'm not trying to convince
anybody to do that. What that seems to
suggest is there is a little bit of an
appetite suppressant effect from these
artificial sweeteners or non-nutritive sweeteners. Now, this gets a little
bit more complicated because if these
were people drinking sugar-sweetened beverages,
maybe they've already developed a sweet taste
and try to go to water, it's too much of
a jump for them.

And so going to having
something like intermediate is a little bit better. Like, there's a lot
wrapped up in this. But these are the randomized
controlled trials, which are a little bit more
tightly controlled, which I tend to default
to a little bit more than I do the epidemiology,
which epidemiology is just so messy, because sure,
non-nutritive sweetener consumption may be associated
with different things, but there's also a whole other
set of lifestyle and habits that are tied up in that. So I tend to hang my
hat a little bit more on the randomized
controlled trials. So understanding that. OK. Now, all things being
equal, understanding that this is a tool that
may help some people, and whenever I post about
non-nutritive sweeteners in the comments, there's
always one or two or three people who say, all I
did was cut out soda.

And I drank diet soda
instead, and I lost 50 pounds. Or I lost 75 pounds. I even had 1%. I lost 100 pounds. That's the only thing I did. ANDREW HUBERMAN: Wow. LAYNE NORTON: I mean, that's a
pretty massive lever to pull. If you consider somebody who
might be having like, I mean, five or six Cokes a
day, I mean, we're talking a serious
amount of calories. ANDREW HUBERMAN:
And that also means that by replacing it with
artificial sweetener-containing beverages, they did not
replace the soda with food. LAYNE NORTON: Correct. So now, let's talk about, right? This is where we can get
into the micro analysis, but is that obese person who
lost 100 pounds by doing that? Do I really care about,
maybe, a small alteration to their gut microbiome? No, because their gut microbiome
is actually much more healthy now by them having lost all
that excess adipose tissue.

So again, the ranking of
what I'm worried about can change depending on
the specific situation. Now, let's take somebody like
me who's lean and doesn't really have any health problems
that I'm aware of. What about artificial
sweeteners for me? Well, for me, I got using them
because of bodybuilding contest prep, because it was
about the only appetite suppressant that worked for me. But do I think that
they are healthful? Probably not. Do I think they're unhealthy? I would say based
on the current data, I don't think that
they're unhealthy. Now, the information
on blood glucose. So there's– some of the
problems with some of these meta analyzes or these
reviews is they lump all the non-nutritive sweeteners
together and then they may say, well, there's no effect on this
or there's an effect on this. Well, the problem is these
are different molecules and they can
interact differently. Aspartame, very clearly,
seems to have no effect on blood sugar or insulin.

That has been repeatedly shown. Stevia doesn't appear
to have much effect. Saccharin and sucralose,
the jury is mixed. Now, there was the
study that we first connected on which, I
think, their primary outcome measure was actually they were
looking at the sweet taste. Like how it affected
sweet taste. So what they did was, the group
that was getting the sucralose was also paired
with maltodextrin. The control group
was getting sucrose, which is an appropriate
way to compare the sweet taste because
maltodextrin is not as sweet as sucrose. So when you're trying to
combine sucralose, which is already sweet, with
another form of carbohydrate, you'd want something less
sweet compared to your control.

But for the outcome measure
of insulin and blood glucose, probably, not as
appropriate because we know maltodextrin has a much higher
glycemic index than sucrose. ANDREW HUBERMAN: So they
appropriately controlled for taste, but not for the
effect of the sweeteners. And I think that that
was a key component. And I think, yeah, the
part of that study that intrigued me actually was
in a talk version of that because that study drove
me to watch a talk that– and we'll get Dana Small on
the podcast at some point, hopefully– was that they
had kids do this study.

And they actually had
to cease the study because a couple of the
kids became prediabetic. I mean, it seemed like there
was something hazardous about– this was the Yale
School of Medicine. It's a good place. I mean, there's a
range everywhere. But it just seemed like there's
something about sweet taste that if taken to
the extreme might be able to impact blood sugar. This has impacted my behavior. And I try to avoid really
sweet things, unless they're exceptionally delicious or
the occasion calls for them because I do think
that it increases my craving for sweet things. LAYNE NORTON: Well, it might
not be necessarily a craving, but it just programs you. Your taste buds are
extremely adaptable.

So take, for
example, Indian food. If you bring Indian
people over to America and have them eat
some of our food, they think it tastes extremely
bland because they're used to such spicy
food that unless they have a certain level of spice,
they can hardly even taste it. If you've ever done
a high-sodium diet and then gone to a low-sodium
diet, it feels very bland. ANDREW HUBERMAN: That's
where I started from.

LAYNE NORTON: But over time,
your taste buds adjust. So sweet is the same thing. If you're used to
eating a lot of sweet, you get desensitized to it. And then if you go to
something less sweet, it can taste-bland at first. Over time, it'll get better. So I think it's
one of those things that, again, it depends
on the situation. If somebody's obese
and they said, well, this is going to
help me eliminate sugar-sweetened
beverage, why would you want to take that
tool away from them? That's a great lever to pull.

I mean, if somebody can
lose literally 100 pounds from just one change in
lifestyle that's not even really that inconvenient of
a change, that is powerful. But again, is it the most
healthy thing they could do? And I think that's what
tends to get asked. We don't know. Is it healthier than water? Probably not maybe
as healthy as it. Who knows? But I really make
all those caveats because you don't want to
have people who could use this as a tool to think, well, no,
I can't do this because it's actually bad for me. If it helps you lose
50 pounds or 75 pounds or whatever it is, trust me,
it's not bad for you, right? ANDREW HUBERMAN:
Well, it does seem to increase your
satiety signals. What do you think about
the microbiome effects in this recent study? Because the recent
study, I think, had some nice features to it. And you've done a detailed
description of the study.

So for those that want that– LAYNE NORTON: Is this the
two-week study or the 10-week? ANDREW HUBERMAN: Yeah,
the two-week study. Yeah. And we will provide a link. You did an excellent video
on your YouTube channel that really parses each piece. But they compared the
various artificial sweeteners and looked at the glucose
response, looked at microbiome, a number of different measures. What was your general takeaway? And this was in
humans for, I think, the first time looking
at microbiome in humans due to artificial sweetener– LAYNE NORTON: There
are a few studies on the microbiome in humans
with artificial sweeteners. The first two that came out
showed pretty much no effect, but they were a little
bit shorter in duration.

They were two to four weeks. And again, it depends on what
bacteria are getting measured. There's many different
kinds of bacteria, so they could just be measuring
one that didn't change. And then there was a
10-week study that came out that got a lot of press. And they showed– I think it was sucralose. I think. They showed an effect of
change on the gut microbiome. Now, what was
interesting is when I went into the
species that changed, the species that changed the
most compared to the control was a species called– I'm going to butcher
the name, but it's like Blautia coccoides,
I think it's called.

ANDREW HUBERMAN: I
must say for those that work on the microbiome,
it's so difficult to pronounce. I mean, you need a
nomenclature committee, and you need acronyms. I'm sorry. Just do it. LAYNE NORTON: [LAUGHS] ANDREW HUBERMAN: Enough already. You're killing us. LAYNE NORTON: We'll call it BC. We call it BC. ANDREW HUBERMAN: BC, thank you. We're going to start the
nomenclature committee without you if you
don't do it soon. LAYNE NORTON: So they noticed
that this went up by, like, three- to four-fold. So I kind of went down
the rabbit hole on this. So interestingly, that
particular species of bacteria is actually associated with
lower adiposity, better insulin sensitivity. And people who are obese
and children who are obese tend to have less of it. So I said, well,
based on that study, you can actually argue that
maybe sucralose actually improves the gut microbiome. Now, again, I'm not
making that claim. Because we have a hard
time understanding what a healthy microbiome
looks like already. This last study that came out,
my biggest take-home was I think it's safe to say that
some of these non-nutritive sweeteners are not
metabolically inert.

There are some effects. Now, are those effects
good, bad, or neutral I think has yet to
be fully elucidated. Now, I focused more on the
blood-glucose responses in my analysis. So in that 10-week study, they
did oral-glucose tolerance test. And their conclusion I
didn't really feel like fit their data. So their conclusion
was that– and again, I think it was sucralose– that it elevated blood glucose. [SIGHS] And this
is where statistics can get kind of tricky. So my take-home was the
area under the curve, the incremental area
under the curve, which is looking at basically
the entire glucose response, was not different
between the control and the sucralose group. To me, that's the
biggest take-home. There was one time
point at the end of the study in the sucralose
group, the 30-minute time point, that was statistically
significantly higher blood glucose than the control group. It's kind of one of
those things where I go, OK, it was one time point. It's statistically significant. But even then, we've seen
things be statistically significant that end
up being data artifacts because they're not reproduced.

So I'm not saying that's
what's happening here. But again, the overall
area under the curve was not different. So to me, that was
the biggest take-home. ANDREW HUBERMAN: And papers,
we should probably mention, are published because
of effects, generally. [CHUCKLES] Lack of
effect, harder to publish. LAYNE NORTON: Null
hypothesis doesn't– it's actually really unfortunate
because a null hypothesis is just as useful data as
the non-null hypothesis. But you're right. There is a very strong
publication bias towards showing an
effect versus not. ANDREW HUBERMAN:
Yeah, unless you can flip a field on its head
entirely by showing something did not happen, typically
the positive result out does the negative
result, positive meaning you see a result.

And then
of course, it's one study. And– LAYNE NORTON: Yes. ANDREW HUBERMAN: –I think that,
as you talked about earlier, the center of mass of
data in a given field are probably the best basis for
what we should do in terms of– and so I'm not changing my
behavior around the intake of artificial sweeteners. I personally am still going to
consume stevia and aspartame in relatively small amounts.

LAYNE NORTON: Yeah. ANDREW HUBERMAN: But
now I'm thinking, well, OK, if something
contains sucralose, I don't have to perhaps
actively avoid it. Whereas before I was. I was actively avoiding it. LAYNE NORTON: So the
new study I thought was very elegantly–
very involved. I mean, to be quite
frank, some of the animal stuff they did was
extremely impressive. So there was actually
two arms to the study. One was the human arm. One was the animal arm.

I focused much more on
the human side of it. So basically, this
was a two-week study. And the really unique aspect
of this, which I think is both a strength
and a weakness, they had almost 1,400
people apply for this study. And they only had 120, I think,
that actually went into it. Because they did a very detailed
food analysis of these folks. All of these people
said that they avoided artificial sweeteners
or didn't consume them. And I think people don't realize
how ubiquitous sweeteners are. ANDREW HUBERMAN:
Prior to the study, these people were like–
it was like jury selection. They'd never– LAYNE NORTON: Yes. ANDREW HUBERMAN: It's
like not ever hearing of the plaintiff
and the defendant. These are these mutant
people who have never had an artificial sweetener. LAYNE NORTON: Right,
so the strength is now you don't have a lot
of preexisting effects that may be clouding
what would actually happen when you add it in. For example, if you have
people who are already consuming artificial
sweeteners and then you have them consume
artificial sweeteners, the likelihood things are going
to change is pretty low, right? So I think that
that's a strength.

It's also a weakness. And I want to be really
careful because I think people took my words
a little bit too far, which means I probably didn't do
a good job of being nuanced enough. There is the possibility
for a placebo effect here. So to me, if somebody has gone
through that much painstaking care to avoid
artificial sweeteners, it's likely they have
a preconceived notion that those are bad for
you, because they're difficult to avoid. Yes, it's possible if they're
eating a very minimally processed diet that they're
just not exposed to them. And that's very true, as well. But the other thing
that the researchers acknowledged was they weren't
able to blind the study.

Because if you've never had an
artificial sweetener before, you're only used
to regular sugar and you have an artificial
sweetener, you know. ANDREW HUBERMAN: You taste it. LAYNE NORTON: You know. It's still sweet. But it's not the same sweet. ANDREW HUBERMAN: And there's
an interesting effect there, where a lot of people don't
like the taste of aspartame the first time. I actually quit drinking
diet soda for a while, thinking I should,
and then had one.

It tasted really– I can only describe it as
kind of artificial, chemical. And then pretty soon,
it tasted great again. LAYNE NORTON: Yep. ANDREW HUBERMAN: And so there
is some attenuation there. And whether or not
that's central, meaning within the brain,
or peripheral, I don't know. But very interesting. Well, I see you as playing
a critical role in defining what is and what
isn't, what still needs to be determined in
terms of this landscape and the entire landscape
really of nutrition. LAYNE NORTON: And that study did
change my opinion in terms of, OK, I think we can clearly say
now that these aren't neutral. Or sorry, that they're
not inert, right? That was the thought
process before, was well.

They're not digested or
whatnot, so they must be inert. That doesn't appear
to be the case. But again, when we look at the
blood glucose data, there's– and I'm not saying
this is what happened. I want to be very clear. I'm not saying this
is what happened. I'm saying it's
possible this happened. And so this is why we need
more studies to verify.

If these people had
a preconceived notion that artificial sweeteners
were bad for them, it's possible, knowing they're
ingesting artificial sweeteners that they could have had
a blood glucose response. Now, my pushback on my
own point there would be, then we should have expected to
see it in all the non-nutritive sweeteners, which they didn't. It was just in
sucralose and saccharin. ANDREW HUBERMAN:
Yeah, it was kind of a graded effect, where
sucralose and saccharin showed the most dramatic change. LAYNE NORTON: Yeah. ANDREW HUBERMAN: And stevia and
a few of the others did not. LAYNE NORTON: And
the other issue I took with it– maybe
it's a ticky-tack thing– was their primary
outcome measure was blood glucose, the
oral-glucose tolerance test. But they had people administer
their own oral-glucose tolerance tests, which
basically they gave them– they said, OK, drink this drink. And they were wearing
continuous glucose monitors, which should have been fine.

But again, to me– and I'm being ticky tacky. And again, I know all studies
are limited by funding. So I think overall,
this was a great study. But I would have
liked to have seen them monitor the
oral-glucose tolerance tests to administer it. ANDREW HUBERMAN: Yeah, and
what they did before or after. You want to know that
they didn't ingest this or did ingest that. LAYNE NORTON: Right. ANDREW HUBERMAN: Yeah. LAYNE NORTON: Those two things. But one other caveat is
it was a two-week study. So we've got to be really
careful how much we interpret in this because it's
also possible that this is a transient effect, right? And maybe it goes
away over time. We don't know. But again, I think
we can clearly say it's not inert, right? Now, how much emphasis we put
on that, on a two-week study, I still will say, OK,
maybe if you're worried, don't consume sucralose.

But if you're 100
pounds overweight and you want to use some
sucralose as a replacement to help you lose
weight, I would say, don't let this study
deter you from doing that because the
net effect is still going to be more positive than
you not losing the weight, right? So if it's a tool
that helps you, fine. But I do hold open the
idea that, well, there could be negative
effects from it, as well. But again, we're looking at,
what is the overall outcome? And then they examined some
of the different things that were increased with
these different sweeteners. And again, this word
gets messy because one of the things they
saw was a big increase in butyrate production from the
change in the gut microbiome presumably.

Well, as we discussed
earlier, butyrate's actually associated
with positive outcomes in terms of insulin
sensitivity, inflammation, and some other things. So I want to be real cautious
before people say, well, if there's a change
in the microbiome, it must be a bad change. We don't know. It's possible. And again, if we have 10 more
studies come out and start to show this, then I will start
to shift my personal opinion of artificial sweeteners.

ANDREW HUBERMAN:
So in anticipation of sitting down
today, I did solicit for questions on social media. And one of the questions
that got a lot of upvotes, likes if you will,
was one that I think raises interesting questions
about short-term and long-term health. And it's the following. I think it's a common scenario. A number of people
want to know, what is the healthiest way to
approach a rapid weight loss? And here what I
think is happening is somebody has
an event coming up or they're just tired
of being the weight they are, carrying the amount
of adipose tissue they are. And they wanted to
know whether or not it is safe to,
for instance, lose three pounds a week for a
few weeks in anticipation of a wedding or some other
event and whether or not straight caloric restriction
and increasing activity is the best way
to approach that, with the understanding that
they may gain back a little afterwards.

I think ideally they'd like
to maintain it afterwards. But what do you think
of that approach, cutting caloric intake
in half, for instance, and then also doubling
your physical output? LAYNE NORTON: So
it's interesting because you might
be surprised by what I'm going to say, which is the
research data actually tends to suggest that
people who are obese, who lose a lot
more weight early, are more likely to
keep it off, which seems a little bit
contradictory, right? Like, well, that doesn't
seem very sustainable. But again, you're
weighing competing things. So there's the
sustainability aspect. But then there's also– buy-in
is huge for sustainability. So for a lot of overweight
or obese people, if they start a diet and they
don't see something quickly, they bail on it because
it's not working. Whereas if they see some
rapid results pretty quickly, they buy in even harder. And so I think that the
conversation, especially for if there's any coaches
or trainers out there, is just presenting that as the– one of my favorite lines
is there are no solutions.

There's only trade-offs. I think Thomas Sowell said that. So you're having
a trade-off here. Yes, you're going
to lose fat faster. You might lose lean
mass a little bit faster too, which
can be a problem. But I will say, the more
adipose tissue you have, the more aggressively
you can diet without negative consequences. Somebody like me doing
a really aggressive diet is not going to be
good for my lean mass. One, I have a higher
lean mass than normal. Two, I have a lower
body fat than normal. As your body fat goes
down, the percentage of weight loss from
lean mass goes up. So people who are very
obese, because they have so much adipose
tissue to pull from, there's very little
reason for the body to metabolize lean tissue. Now, that being said, if you
go on a– people misinterpret, like, well, I got an
in-body done or a DEXA done and I've lost 2
pounds of lean mass, and they've lost
20 pounds overall. Well, keep in mind, adipose
tissue itself is 13% lean mass.

So there's actually
a protein component to– the structural component
of the adipose tissue. And it does have some water. So it's about 87% lipid. But the other part is lean. So at minimum, you should expect
a 13% reduction in lean mass when you diet. And then when you consider like,
you lose body water overall, which registers as
lean mass, and you lose your splenic tissues
can shrink a little bit. So it's normal for the average
person to lose 25% or 30% of the weight that they
lose from "lean mass." But that doesn't mean
skeletal muscle tissue. And again, the more
adipose you have, the more aggressively
you can approach the diet without really negative
long-term consequences to lean mass or
your overall health.

But balance that with, OK,
if I'm going to do this, I need to understand
that I'm not going to be dieting this way forever. I'm doing this to give myself
a boost at the beginning. And I have to be
OK at some point with transitioning
to something that's a little bit more sustainable. ANDREW HUBERMAN: Based
on what you just said, it reminds me of the satiety
signal effect of exercise you mentioned earlier,
that exercising can improve our sense of
when we've had enough to eat. I just want to briefly mention
that when Alia Crum was on the podcast, she
mentioned that they'd been doing a study that– I have to pair you two
and hear the conversation as a fly on the wall. Because what she
was telling me was that if people believe that a
food is nutritious for them, then eating less of it
registers as more satiating. Whereas if people view dieting
as a deprivation system, like, oh, dieting is
hard, and the food sucks, and it's terrible,
well, then they crave all sorts of other things.

Whereas they actually
observe in their studies where people report reduced
craving if they are told, for instance, a chicken breast
and broccoli and some olive oil and rice is actually
quite nourishing. It's actually
really good for you. Then people eat that. And they feel like they've
actually eaten more. The satiety signaling goes up. So it's just a point
that Alia made. Those aren't my data. LAYNE NORTON: Satiety is
so impressive because even the rate at which
you eat and right down to the size of the plate
and the color of the plate, the contrast in color– ANDREW HUBERMAN: Really? LAYNE NORTON: I can't
remember exactly. I think it's if the plate is
a similar color to the food, I think people eat more. Whereas if it's a bigger
contrast, they eat less. So even plate color can make a
difference on how much you eat. So again, human brain,
very amazing, but also very dumb in some ways, right? ANDREW HUBERMAN: Not
an optimized algorithm.

LAYNE NORTON: I always
joke with people. I'm like, just look at
how stupid humans are. You put some water in front
of them, like the ocean, they're like, oh, yeah, I'll
pay 10 times more for this. [CHUCKLES] But we're
kind of wired that way. ANDREW HUBERMAN: The reward
signaling pathways in the brain run one chemical mainly,
dopamine– there are others, of course– and very few algorithms. It's sort of like an– intermittent reinforcement
is one, random reinforcement. But in the end, there
aren't many algorithms. And we are probably not
optimized– certainly not optimized for our
own health because people will eat themselves to death,
drug themselves to death, et cetera, simply because
something felt good at one point.

It proves your point. LAYNE NORTON: Right. One of the things
I tell people– I said this on– for someone's podcast
was, interestingly, the dichotomy of
life is if you do what's easy in the short
term, your life will be hard. If you do what's hard
in the short term, your life will get easier. It's very strange. And actually, Ethan Suplee
had a great example of this. When he was over
500 pounds, he said, the amount of work I had to
do to construct my life that I could just live was
so much more work than just going to the gym
for a couple hours a day.

He's like, the gym work is hard. He's like, but when I
look back at how much work I had to do to sustain that
lifestyle versus just going to the gym and
restricting calories, he's like, to maintain the
lifestyle of being 500 pounds was infinitely more
difficult than what I do now. And so again, great example. Short term– hard. Going to the gym,
calorie restriction. Long term, life's easier. Just a really interesting
dichotomy I think about a lot. ANDREW HUBERMAN: And it can't
be restated often enough. Seed oils. People want to ask
about seed oils. And for– LAYNE NORTON: Cut. [CHUCKLES] ANDREW HUBERMAN:
And for those of you that are listening who are
wondering why we're chuckling already, I should mentioned
that both in the Twitter sphere and Instagram and online, there
are these very polarized views that probably aren't worth
focusing on for too long. But there are a number
of folks out there who are arguing that seed
oils are the source of all– the obesity epidemic– LAYNE NORTON: Everything. ANDREW HUBERMAN:
–inflammation, et cetera– LAYNE NORTON: Illuminati. ANDREW HUBERMAN: –everything.

And then there are those that
would argue just the opposite, that meat is the source of
all problems, et cetera. And I think we've, thanks to
your nuance and expertise, we've hopefully
appropriately framed things that it's never that
black and white. It's simply not. LAYNE NORTON: Rarely. ANDREW HUBERMAN: Rarely. I love olive oil. I realize that
doesn't fit exactly into the seed oil category. I love olive oil. I use it in moderation. I do also consume some butter
in moderation, et cetera. But are there any
data on seed oils? And here, a good
example I think would be canola oil, which comes from
the rape seed, that literally was renamed canola oil
because rape seed oil is not good marketing. LAYNE NORTON: No, no. [CHUCKLES] No, exactly. So the first thing
I'll say is seed oils have negatively contributed
to our overall health because people in the last 20,
30 years, what they have tended to add into their diet that does
increase the overall calorie load is oil, mostly
from seed oils.

But when we look at 1-to-1
replacement with other fats– if you look at the
epidemiology, yeah, you can find some
epidemiology showing people who consume more seed
oil have more negative health outcomes. Problem is, again, tied up with
a multitude of other behaviors. And then you can
find mechanisms. And the idea is, well,
they're polyunsaturated, which means in the
fatty acid chain, there's multiple double bonds,
which those double bonds can be oxidized when they're exposed
to heat and some other things. And so the idea is, well, when
you cook with these things, they make it oxidized. And that's going to cause
inflammation in your body. So that's a plausible mechanism. So as always, I defer to the
human randomized controlled trials. And so what you tend to
find is when you substitute saturated fats for
polyunsaturated fats, it's either neutral or positive
in terms of the effects on– inflammation is
basically neutral. There's some studies that
show a positive effect of doing polyunsaturated fats. But it probably depends on the
individual polyunsaturated fat. And that's the
other thing that's difficult because
you're categorizing everything in this one bucket.

And there are some differences
between individual fatty acids. Even with saturated fat– for example,
stearic acid doesn't tend to raise LDL cholesterol. Whereas saturated fat as a whole
tends to raise LDL cholesterol. But there are some
saturated fats that don't. So again, we're putting
things in buckets. And it's a little more
nuanced than that. Then if you look at the
effects of polyunsaturated fats on markers of
cardiovascular disease, again, tends to either be a
neutral or positive effect when you substitute saturated
fat for polyunsaturated fat. Now, if you want to get
into monounsaturated versus polyunsaturated, there's
quite a bit of disagreement between the studies. What I would say, based on the
human randomized controlled trials, is that
you're probably better off consuming monounsaturated
and polyunsaturated in place of saturated fat. But again, if the idea is,
well, that means polyunsaturated are good for me, so I'm just
going to dump a bunch of oil on everything and now
you're upping your calories, well, that's a negative
now because you have to deal with the bigger
problem of overall energy toxicity.

So I'm not somebody who likes to
demonize individual nutrients. I just haven't seen
really compelling evidence that seed oils are the root
cause of the problems that are being suggested. And I think this is a good
example of whenever there's something that pops up
in the fitness industry, there's always
the opposite thing that pops up and is the
reactionary, extreme reaction to whatever this
thing was over here. And I think that's what we're
seeing with some of the seed oil stuff, is it's mostly
people who are trying to espouse the virtues of saturated fat. And listen, I think it's fine
to consume some saturated fat. But again, I think
limiting it to 7% to 10% of your daily calorie intake
is probably wise, again, based on all the consensus
of the evidence I've seen. And so once again, we're
struggling with this. OK, we've got this epidemiology
and these mechanisms that sound good. But then, what
actually happens when we do some human randomized
controlled trials? And so far, I just
haven't seen the evidence to suggest that seed oils
are independently bad for you, independent of
the calories they contain.

ANDREW HUBERMAN: You said
the words, "overall energy toxicity." And I just want to
highlight that I think that's a fabulous term. I don't think enough
people think about that because they are primed,
or we are all primed, to think, OK, seed oils might be bad. Or artificial
sweeteners might be bad. Or this particular
component of blood work might represent
something good or bad, without taking into
account overall energy toxicity, the toxicity of
overconsuming calories, energy.

And thank you for pointing out
that most of the data point to the fact that saturated
fat should make up about no more than 7% to 10%
of total daily caloric intake. Is there a lower-end threshold
that can be problematic? For instance, I've noticed that
my blood profiles, especially in terms of hormones,
improve when I'm getting sufficient saturated fat. Maybe I'm a mutant. But years ago,
because I'm a product of growing up in the '90s,
I tried a low-fat diet. It certainly crushed
my androgen levels. I started adding
some butter back in. And I was right back
in the sweet zone, where I wanted to be.

So 7% to 10% of total daily
caloric intake, I'm guessing, is probably about what I do now. I'll have to check. But is there a danger to going
too low in saturated fats? LAYNE NORTON: So
again, no solutions, only trade-offs, right? What maximizes out
testosterone might not be the best thing for
longevity, and vice versa. I'm not making that
claim specifically. But I think it's important
to understand this that I think we
all have this idea that there's this one
iconic diet out there that is going to be the best
diet for building muscle and burning fat and preventing
cancer and heart disease.

And the reality is, there's
overall healthy dietary patterns that we see that
are good for those things. But when we get
down into the weeds, there's probably some push
and pull here, as well. So when it comes
to saturated fat, there is some evidence that
if you're too low on it, that yes, you can have a
reduction in testosterone. Now, is that reduction in
testosterone, let's say 15%, 20%, whatever it may be, is that
sufficient to actually cause loss of lean mass? That, we don't know. That's never been shown. Interestingly, I
just remembered this. There was one study that was
comparing polyunsaturated fat versus saturated fat. And they equated total fat. And one of the really
interesting things was the group getting
the polyunsaturated fat had more lean mass at
the end of the study compared to the group
getting saturated fat. Now, it's only one study. I've never seen this replicated. So this is a
situation where I say, I would like to find out
what the mechanism of that is because this
could just be random.

But if that gets shown over
and over, what I might say is, OK, well, if
polyunsaturateds are somehow increasing lean mass compared
to saturated fat, who cares what happens with testosterone? Unless that reduction
in testosterone is causing some kind of
impotence for your life, right? So all that to say,
I don't really know. And by the way, that's
something, for those watching and listening, real experts,
every once in a while, you should hear them say the
following words "I don't know." [CHUCKLES] ANDREW HUBERMAN: Exactly. My graduate advisor was
exceptional at that. And she was brilliant, right? LAYNE NORTON: And then in
terms of cholesterol synthesis, you really need a very, very
small amount of saturated fat for LDL cholesterol synthesis.

Your liver can synthesize–
the amount of LDL cholesterol, or cholesterol that
your body requires is so small in terms of just
living and being healthy. So I don't think you
need to worry about that. And from a cardiovascular
disease standpoint, there is some evidence that
even taking people who have, quote, unquote, "low
LDL" of 80 or 90 and taking them down
to like 30 or 40, that there is still a
benefit for the risk of cardiovascular disease. So again, you're weighing
these two buckets. So what I say, if you're doing
7% and 10% from saturated fat, you're probably fine.

ANDREW HUBERMAN: I received
a lot of questions about whether or not there
are female-specific diet and exercise protocols. And I realize this
is a vast landscape. But some of those
questions related to menopause and premenopause. And some related to
the menstrual cycle. Most related to variations
across the menstrual cycle. In terms of, let's just say diet
maintenance or subcaloric diet, are there any things
that you've observed? We'll talk a little bit later
about this wonderful app that you've produced,
this Carbon app which helps people manage
their energy intake and a number of other things. And so there, you have
a sort of a database, or at least an experience base. And then I'm guessing there
are probably also studies exploring male-versus-female
differences in terms of adherence and what
sorts of diets work.

Are there any general themes
that one can extract from that? LAYNE NORTON: This is going to
be a really unpopular segment for the women. Doesn't seem to make
a big difference. ANDREW HUBERMAN:
Well, actually, they may be relieved to hear
that because it makes sorting through the
information space and certainly the
information we've covered in this podcast
up until now simpler. It means that everything
isn't different for them. LAYNE NORTON: Yeah,
so if you look at the male-versus-female
studies' relation to diet, they seem to respond
in a similar way. Like, similar
calorie deficit seems to produce similar results. If you do low carb, high
carb, regardless, it seems to boil down to
the same principles. Now, training wise, we
do know that females, the muscle fibers adapt a little
bit differently to training. But without getting
too far into the weeds, it doesn't really
change the way you should train because for the
most part, building muscle, there's a lot of different
ways to build muscle.

So we know that light
loads up to maybe 30 reps, as long as it's taken close
to failure, have basically the same effect on
building muscle, at least in the short term,
as heavy loads for low reps. It's mostly about
taking the muscle close to fatigue or failure. You don't have to go to
failure, but getting close, within a few reps. If you're between
one rep and 30 reps, if you're getting
close to failure, seem to produce similar results. So again, great.

You can pick whichever form of
discomfort you prefer, right? When it comes to
female-specific training, again, females
actually– this is one thing that a lot
of people don't know. They actually put on a
similar amount of lean mass as a percentage of their
starting lean mass as men. In fact, there's no
statistically significant difference in the amount
of lean mass they put on. Now, the absolute amount
of lean mass that's added will be greater for men because
they started with a greater amount of lean mass. But the relative
increase in lean mass is pretty much the same
from similar training.

Now, females, there's some
differences in fiber types, that females tend to be a little
bit less fatiguable than men. They can go a little bit
harder a little bit longer. And there's also some
evidence that they recover a little bit better. But that also could be
simply due to the fact that they're not able
to use as heavy of loads to induce hypertrophy. So I kind of have this theory
that while as a percentage of your one rep max,
you can program things, I think absolute load matters. When you look at the
most elite power lifters, the super heavy weights aren't
squatting three or four times a week because they're
squatting 800, 900 pounds.

ANDREW HUBERMAN:
They need to recover. LAYNE NORTON: I think that
there's an overall recovery effect there. Again, I have no
data to back this up. This is just my observation. But when you get into the
lighter weight classes– and this goes for
men, too– you do see quite a few people
who do many training sessions at high
RPEs and seem to be able to recover from that. So I do think the absolute
load makes a difference. Now, when it comes
to menstrual cycle, this is one of those things
where I kind of tell people, do what you prefer. So there are some
people who have said, you should schedule
your training around your menstrual
cycle, which is whenever you're going
through your menstrual cycle, reduce the intensity.

Reduce the volume because you're
not going to feel as good. You're not going
to train as well. What I would say is
just autoregulate that. If you go in and you're on
your period but you feel good and you're doing
well that day, then I don't think you necessarily
need to back it off. And there was one study that
kind of supported that notion. But if you go in and
you feel terrible and you feel like you could
use a reduction in intensity and volume, then it's totally
fine to autoregulate that. And when I say
autoregulation, autoregulation means you are regulating the
individual training session based on your performance.

So I autoregulate insofar
as, I'm a super nerd. So I have a velocity device. So I can actually
attach it to the bar and see how fast the load moves. And I know at various
different warm-up weights what velocities I should be hitting. So if I hit my last warm-up
and my velocity is about 10% higher than usual, I
can be pretty confident that that's going to
be a good day for me.

If it's lower, than I can
back it off a little bit. In fact, at Worlds, when I
hit my last deadlift warm-up, it was 30% faster than I
usually hit in the gym. And I turned and
looked at my coach and I said, yeah, we're
going to get this today. [CHUCKLES] So there's various forms
of ways to autoregulate. But again, women, if you're on
your period but you feel good, I don't think there's any
reason you need to back off. But if you're not feeling good,
then it's totally appropriate to back off. ANDREW HUBERMAN: Raw
versus cooked foods. People wanted to
know whether or not, for instance, eating
a raw apple versus– I don't know. Does anyone cook apples? People used to bake– baked apples was a
dessert when I was a kid. It was kind of the
letdown dessert. Sorry, Mom. That was not awesome unless it
had a scoop of ice cream in it. LAYNE NORTON: Or apple pie. ANDREW HUBERMAN: And even
then, maybe not awesome.

But anyway, raw versus cooked. Obviously, if you
burn a piece of meat to the point where it's pure
charcoal, that's too much. And there is a small movement
surrounding eating raw meats. That's not something
I particularly enjoy. Frankly, sushi is the only
raw food I personally ingest. LAYNE NORTON: Same. ANDREW HUBERMAN: And I am
very careful about the source, frankly– reputable places. Is there anything
real about this in terms of being
able to extract the amino acids, vitamins,
and minerals from the food raw versus cooked? LAYNE NORTON: It just
looks cool for Instagram. So when you cook foods, they
actually tend to become– in terms of
protein-containing foods, they tend to become more
digestible, not less. Eggs are this way. Meats are this way. People say, well, when you
heat protein, you denature it. And I think they hear
that word "denature," and they think destroy. And that is not
what denature means.

So proteins fold up into
3D dimensional structures, you know this of course, based
on their amino acid sequence. And there are specific
energies of those amino acids. When you heat
protein or add acid, it starts to unfold
that protein structure. That happens during
digestion anyway. So I always chuckle when– I've seen some
companies come out with "way that
you can cook with" that's not going to
destroy the amino acids.

And I'm like, so you
mean regular way, right? So yeah, typically,
cooking actually makes amino acids more
bioavailable, not less. Now, I would stay away
from charring your meat because there is some
evidence that charring creates polyaromatic hydrocarbons,
which at least in animals, when they give those, they
appear to be carcinogenic. So if you do char
your meat by accident, I would just cut off
the charred portions. And then you should be fine. ANDREW HUBERMAN: The
char is delicious. LAYNE NORTON: [LAUGHS] ANDREW HUBERMAN: Not if
it's charred too much. But there is something about
a charred crust on a meat. My dad's Argentine and likes
a good charred barbecue. LAYNE NORTON: Oh, yeah, yeah. ANDREW HUBERMAN: What about– people referred to them in their
questions as "carb blockers." But I think what
they're referring to are things like berberine and
some of the glucose scavengers.

And one glucose scavenger I'd
love for you to comment on is this assertion that taking
a brisk walk after a meal, or maybe even a slow
walk after a meal, some movement can help downshift
the amount of circulating glucose in some way. I've heard that. Not a lot of people, but some
are starting to pay attention to this idea of taking
things like berberine or even metformin
can scavenge glucose. I personally can't
take berberine. If I take it, I get
massive headaches unless I've ingested tons
of sugar and carbohydrates. So I just don't
mess around with it. But I know there are a
number of people out there that want to know whether or
not these glucose scavengers can be useful. LAYNE NORTON: I think that is
really majoring in the minors, if I'm being honest.

As far as the carb
blockers, there's some white kidney bean extract
and those sorts of things. They do block the digestion
of carbohydrates, some. So when I say "block,"
those watching or listening, metabolism is typically
not on and off switches. So when we say things like
"block" or "attenuate" or "inhibit,"
typically we're not talking about just a switch
on the wall that you press it, and everything turns off. We're talking about
a dimmer switch, OK? So it just changes the emphasis. But these carb
blockers can reduce the absorption of carbohydrate. Now, they don't seem to cause
weight loss when you just do it in a normal diet. Now, why is that? Well, all it does is once
those carbohydrates get to the large intestine and your
bacteria get a hold of them, they start fermenting them to
volatile fatty acids, which get reabsorbed into your liver.

So you don't get the
increase in blood glucose. But you still get almost
all the calories from it. It's just in a different form. ANDREW HUBERMAN: I see. LAYNE NORTON: So carb blockers,
if they actually worked really well, I mean, if you block
something from being absorbed, your GI typically does not just
let undigested material sit in there. You get diarrhea. I mean, that would
be the outcome. It's also how I debunked the
whole 30 grams of protein at a meal, you can't
absorb any more than that. I'm like, if that was the
case, when you ate a steak, you would just start
having diarrhea every time you went over that
30-gram threshold, right? ANDREW HUBERMAN: I
remember during college– so this would be early '90s– there was the Olestra craze.

LAYNE NORTON: Oh, yeah. ANDREW HUBERMAN:
This idea of putting in a nondigestible thing
into things like potato chips so that it would clear
through the GI tract faster, not absorb
as many calories. This went nowhere, obviously. You don't hear
about this anymore. But it does raise an
interesting question related to energy balance,
which is gastric emptying time. And obviously, in the
landscape of eating disorders, in particular anorexia. Use and abuse of
laxatives is a way in which people will,
in an unhealthy way, try and control their weight. And there's a lot of
problems with that approach. LAYNE NORTON: Oh, yeah. ANDREW HUBERMAN: But what
about gastric emptying time? Is this one way that people
could control their energy balance in a healthy way? And where does fiber
come into play? LAYNE NORTON: Fiber tends
to improve GI transit time because it adds bulk.

So your GI system
is basically a tube. And it has peristalsis, which
is wavelike contractions that moves the food down
through the tube. Well, if you have more bulk
to the food, like with fiber, you can move it through
a little bit better. Now, in the gastric, the
stomach specifically, fiber tends to delay gastric
emptying and slow it a bit, probably because it
congeals a little bit. Now, this gets into the
glycemic index argument, right? If you do low GI
foods, you'll have a slower release of glucose. It's a slower gastric
emptying time. Does that affect energy balance? And so there are
quite a few studies looking at low GI
versus high GI foods. In the studies where they
don't control calories, low GI tends to
outperform high GI. But when they control calories,
there's no difference.

And so what I
think that suggests is low GI foods,
just by their nature, tend to be higher in fiber. And so I think it just kind of
comes back to the fiber issue. ANDREW HUBERMAN: Got it. I'd like to ask you about
supplements for a moment. It's an enormous landscape. But I believe there are a few
things that you believe in, meaning they exist. And there are decent data
to support their use. Maybe even some anecdotal data
based on your own experience, as long as we highlight it as
such, it could be interesting. I've heard you talk about
two in particular, one that I'm very familiar with,
which is creatine monohydrate. If you could share
your thoughts on that, not just for muscle building
but maybe any other purposes for it. And then the other one
is one that frankly I'm learning more about
all the time now, thanks to your prompt,
which is Rhodiola rosea– I think I pronounced
that correctly– and why that might
be interesting or of use to people. LAYNE NORTON: Yeah, so
touching on creatine, it is the most tested,
safe, and effective support supplement we have.

I mean, there are thousands of
studies on creatine monohydrate now. And I would say
very clearly, too, if you're using any
other form of creatine, I think you're
wasting your money. Creatine hydrochloride
has some hype around it. Apparently, it's a
little more soluble. The claim is that you need less. But there's only a
couple of studies on it. And it's more expensive. ANDREW HUBERMAN: And
creatine monohydrate is not particularly expensive. I realize people have
different budgets. But it's not a budget breaker. LAYNE NORTON: Yeah, it's gotten
more expensive because of COVID and supply chain issues. There's forms of creatine
that appear to be as good, like hydrochloride. But it's more expensive. And then things like
creatine ethyl ester has been shown to be worse
than creatine monohydrate. Buffered creatine
is as good or worse. And it's much more expensive. So I tell people, just
take creatine monohydrate. It is tried and true. It's been shown to saturate
the muscle cells 100% with phosphocreatine.

And that's what you want. So creatine works through a
few different methodologies. One, through increasing
phosphocreatine content, which helps improve
exercise performance. It also appears to
improve recovery. And it increases
lean mass, a lot of which is through bringing
water into the muscle cells. But I mean, muscle
cells are mostly water. So when people say,
well, it's just water, that's what
muscle cells mostly are. And it also increases strength
and some other metrics. Now, it also has
been shown in studies that people tend to
get a decrease in body fat percentage. Now, that's probably
because they're getting an increase in lean mass. And so the relative
is a decrease in body fat percentage. But there are a few studies that
show a decrease in fat mass, as well. I don't think that
creatine is a fat burner. I think that people are
able to train harder, build more lean tissue. And so that's probably
having an effect on fat mass.

Then they've actually
shown more recently some cognitive benefits
to creatine, which I find really interesting, as well. But the only knock on creatine
that anybody's been able to come up with– because
they've debunked the kidney stuff; they've debunked
the liver study; there's no evidence that it
harms healthy kidney or liver– is hair loss. So what about hair loss? Because there was
one study in 2009 that showed that
creatine increased DHT. But they didn't
really show an effect on any other sex hormone. So it's kind of strange. Like, you would think if
there was an increase in DHT, there would be something
else that changes, as well. And it's only one study. And again, didn't directly
measure hair loss. It measured DHT, which
we know is involved in the loss of the follicle. So what I would say is
that I am not convinced.

It's only one study. Never been replicated
to my knowledge. And it was looking at
a mechanism rather than an outcome. So if you're somebody
who's prone to hair loss and you want to avoid creatine
because of that, I understand. But for most people, I
don't think it's something to worry about. ANDREW HUBERMAN: Do you
emphasize the classic loading of creatine, taking it
a bunch of times per day and then backing off? Or just taking it
consistently at the– I think 5 grams per day is the
typical dose that people take. LAYNE NORTON: So again, no
solutions, only trade-offs. You can load it. And you will saturate your
phosphocreatine stores faster, usually within a week.

If you just take
5 grams per day, it'll take two,
three, four weeks. But you will get
to the same place. And you're probably
going to have a much lower risk of GI issues. Creatine can be a gut irritant. If it is for some folks, I
would recommend splitting it into multiple doses, so
maybe multiple 1- or 2-gram doses per day. And definitely don't load
it if you're somebody who has GI issues from it. As far as Rhodiola
rosea, the research is still in its infancy. I was just reading a
new systematic review that concluded that we need
more high-quality research. But the research
that is out there seems to suggest
that not only does it reduce physical fatigue.

But also reduces the
perception of fatigue and may also enhance memory
and cognition, as well. And it's referred
to as an adaptogen. So I really like it. My anecdotal
experience is when I combine that with caffeine,
it tends to smooth out the effects of caffeine. It's a more pleasant experience. And there's also some evidence
that if you're coming off caffeine, that it can
reduce the negative side effects to caffeine
withdrawal, which, by the way, I didn't really believe
in that until I actually did a cold turkey– so before a meet, I will cut
out caffeine for seven days because you can basically
reset your caffeine tolerance in seven days.

And two days in, I
mean, I'm groggy. I've got the headaches. Usually, I'll get body aches
that come up because caffeine is actually a mild analgesic. And yeah, so it was
very interesting to see- but I slept like a baby,
I'll tell you that. I slept like a baby. ANDREW HUBERMAN: And
then you took caffeine prior to your event– LAYNE NORTON: To the meet. ANDREW HUBERMAN: So you really
want the maximum punch from it. LAYNE NORTON: Yeah. ANDREW HUBERMAN:
That's why you do that. LAYNE NORTON: Yeah. And like I said,
Rhodiola tends to– it doesn't eliminate
those negative effects.

But it tends to dampen
them a little bit. So I really like it. Again, would like to
see more research on it. But there's a lot
more stuff coming out. Ashwagandha is another thing
that looks pretty promising. Seems to increase
testosterone modestly. ANDREW HUBERMAN: Interesting. LAYNE NORTON: They've shown
increases in lean mass. I don't think the
increase in testosterone explains the increase
in lean mass. It's just not a big
enough increase. ANDREW HUBERMAN: Could it
be the decrease in cortisol? People have talked about– LAYNE NORTON: It's possible. It does decrease
stress hormones. It also has been shown
to help with sleep. But I would like to see
more research looking at, mechanistically, how it's
increasing lean mass before I say conclusively that
this is the next creatine. There's more research
that needs to come out.

And then there's some other
things that have an effect. Citrulline malate, there
was a new meta analysis that showed that
citrulline malate can reduce fatigue and increase,
I think, time to fatigue. And it may actually have
some small recovery benefits, as well. Different forms of
carnitine can actually have recovery benefits. And actually– interesting– I
think it's carnitine tartrate actually has been shown– Volek published a
study that actually showed that it increased
androgen-receptor density in muscle cells. ANDREW HUBERMAN:
That's interesting. L-carnitine and its
other forms are pretty– I think there's good
evidence that they can improve sperm and
egg health for people who are looking to conceive. LAYNE NORTON: Oh, interesting. ANDREW HUBERMAN: Yeah, there
are a surprising number of studies on this in humans. But yeah,
androgen-receptor density– and that's from
oral L-carnitine. People are taking capsules,
not injecting directly into the muscle, yeah. LAYNE NORTON: And then
you've got things obviously like the other most effective
supplement out there is probably caffeine. I mean, if you look at
the research studies, caffeine produces
very consistently improvements in performance.

So that's another one. Some people don't like
the effect of caffeine. That's OK. But– ANDREW HUBERMAN: I wouldn't know
because I've never come off it. [CHUCKLES] LAYNE NORTON: Exactly, exactly. Well, interestingly,
they do show that the effect appears
to be consistent, that even if you're a
habitual caffeine user, you do still get a benefit
every time you take it. But like you said,
you're just used to it. So there's those things. Then you've got things
like beta alanine, which it's in our preworkout. Probably not super helpful
for most people for resistance training. It does seem to have some
benefits for high intensity. If you get out more than
45 seconds or 60 seconds of really hard
training, it does appear to help with delaying
fatigue for that. And then you've got
things like betaine, or also called
trimethylglycine, which there's some evidence it
can improve lean mass. There's some evidence that
it can improve power output. So there's a few
things out there. But most of the stuff
is not very good. So I think that those kinds
of supplements, very useful.

But again, I would never tell
people they need supplements. Again, even something
like creatine is going to be a very
small effect compared to proper nutrition,
recovery, and hard training. One of the things– I was talking with Ben
Bruno the other day. And I said, you
know, some people will ask me like, how does
this person make progress? Because their programming
is not evidence-based? Or this guy, his
exercises are dumb. And I'll say, yeah, but
they trained really hard for 20 years. One commonality you see between
really successful athletes or bodybuilders is
they train really hard. And one of the things
I have observed is the more into the
weeds people tend to get– and again, this is just my
own anecdote and observation– the more in the weeds they
tend to get, the less hard I see them train.

And so one of the
things I really like that Mike Israetel
said, who's got a PhD and is a bodybuilder
himself, he said, you can't outscience
hard training, that if you're looking
to build muscle and you're looking to improve
your body composition, the main thing is just
doing the work over time. ANDREW HUBERMAN: Consistency
and the hard work. And I would add to that–
and this is true of academic endeavors, too, of course;
I hope you'll agree– LAYNE NORTON: Absolutely.

ANDREW HUBERMAN: –which is
that, yeah, the other thing is, given the mental
side– earlier we were talking about how
satiety signals in the brain and what you think about
foods can be relevant. Learning to really enjoy
training hard in addition to learning to really
enjoy eating well, not just for the effects that
it has on body composition– those, too, of course. But just learning to really
enjoy the process of training hard and a really hard
workout or a really hard paper that you have to sort
through or really digging through a book
that's challenging, learning to really enjoy that, I
think, if there is a power tool out there, it's the
psychological end. LAYNE NORTON: And I
think a lot of that is getting the confidence
of doing something hard, that there's a
payoff at the end. I get asked a lot in my Q&As,
how do I get more confident? How do I become more confident? And I'll tell people,
you have to do. There's no hack. You can't read about it. You've got to get in the arena. And I don't mean like compete
in sports necessarily, but doing a PhD or doing something, just
something hard, where you're putting yourself out there.

And you're saying,
this is my goal. And I'm going to go for it. You just learn so much by
doing that about yourself. And so just what you said, I
will reframe things in my mind when bad things happen from– it's not to say I never get
stressed out, because I do. And it's not to say that I
never get down, because I do, because I'm a human. But when something bad happens– I actually posted about
this in my story today. When something bad happens,
very rarely anymore do I go, woe is me. Why did this happen to me? Because you're in the universe. Random bad things
are going to happen. So instead, I say– if I'm not dead– instead, I say, well, what
an exciting opportunity to overcome an obstacle. And I bet, because in the
experience of my life, the biggest lessons and
the best things in my life have actually come out
of the most challenging, worst things that have happened.

And so again, I
would never have been able to do these sorts of
things if I hadn't taken up weightlifting, because
weightlifting taught me so much about perseverance,
delayed gratification, overcoming obstacles. And that's why I love
it even to this day. And I'll still get
butterflies when I go in for a squat
session, even though I've been doing it for 23 years. ANDREW HUBERMAN:
That's wonderful. Well, it's clear that
you embrace hard things. And for people listening
to this, obviously it doesn't have to
be weightlifting– picking hard things,
learning an instrument, learning a language. Challenge is an
absolute builder. LAYNE NORTON: And
they've actually shown those sorts of things,
when you challenge yourself and also mentally, I think there
was a new study that came out basically showing a reduction
in the risk of Alzheimer's and other age-related
cognitive decline.

I mean, basically, use
it or lose it, right? ANDREW HUBERMAN:
Yeah, the desire and the will to persevere no
doubt translates to this thing that we call the
will to live, right? It's related to
the will to live. Well, I think that what
you just said beautifully embodies what most people are
aspiring to, which is to– I think most people actually
want to do hard things. They don't just want
to have the results. I think that most
people deep down have some understanding that
their reward system works that way. I must say, this
conversation for me has been tremendously rewarding. First of all, it
allowed me to meet you in person for the first time,
which I've really enjoyed. Certainly, this won't
be our last interaction on this podcast and elsewhere.

Also, the amount of knowledge
that you contain inside you is astonishing. And– LAYNE NORTON: There's a lot of
stuff rattling around up there. [CHUCKLES] ANDREW HUBERMAN:
And we all benefit because your ability to pull
from the mechanistic side, again I think not
limited to but related to your background in
biochemistry, all the way through to the impact in
humans, animal studies, being able to understand
where those sit relative to one another. And then you're
obviously a practitioner.

You practice what you preach. And what you talk about
pertains to men, to women, younger people, older
people, people who are vegan, Keto, carnivore. You really are able to net
a tremendous number of ideas while staying really
nuanced and data driven. And so I just want to say
for myself and on behalf of the listeners,
really appreciate you coming in here today and
sharing with us your knowledge. We will absolutely point people
in the direction of where they can learn more about you. And one of the places
that I definitely want to mention before we part,
however, is this Carbon app. And I should just mention
this isn't a paid promotion or anything of that sort. Actually, one of our
podcast team members has been using Carbon
for a long time.

This is an app that
you devised which allows people to navigate the
exercise, nutrition, and energy balance space for weight loss,
muscle gain, fat loss, weight maintenance. I would just like to
briefly ask you about that before we conclude. Without necessarily
telling us everything that's in the
Carbon app, I'd love to know, what are the
major things that it does and is good for? And then, what were
some of the key things that you wanted to
make sure were in there when you built it? What's the logical
backbone behind it? Because I think there
are a lot of food counting, calorie counting,
exercise apps out there.

Everyone I've
talked to that uses Carbon, including
our mutual friend, Saagar Enjeti, this member
of my podcast, et cetera, raves about it. So what is Carbon? And what does it do? And what was your
mindset in building it? What did you really
want to see there that you didn't see elsewhere? LAYNE NORTON: So those
listening may not know, but I started online
coaching people for nutrition back in 2005. And that was the vast
majority of my business all the way up until 2017. And I had a lot of
success with that, whether it be just average
folks looking to lose weight or build muscle and
right up to elite level competitors in physique sport. So I had this idea, like– I don't want to
say I had the idea. A few people had the idea. What if we could take
what I do in coaching and try to automate as
much of that as possible? Because by the time I was
becoming a really popular coach, I mean, I was expensive. You were looking
at me charging– I got to the point where I
was charging about $1,000 a month for coaching.

And most people
cannot afford that. And I would like to not
just coach rich people. [CHUCKLES] You know what I mean? I would like to be able
to help other people. So the idea was to
create an app that could do some of this stuff. Now, there's always a place
for human interaction. But for people who
can't afford that, our app is basically
$10 a month. And basically, what we wanted
to do was set up an app where– think about if you went
to a nutrition coach. What would they do? They would probably ask you
some questions about your goals, take some anthropometrics,
maybe dietary preference. And they'd use that information
to kind of formulate a baseline plan. That's what Carbon does. So I think there's eight
questions in the signup flow about your activity,
your exercise, your lifestyle, your body weight, your
body fat percentage. And if you don't know it,
we help you calculate it. It's not perfect. But it's better than nothing.

And then your
dietary preferences. And we use that to come
up with your baseline. And your baseline will be
your calories, your protein, your carbohydrates, and fats. And what's different
about our app– because apps like
MyFitnessPal or whatever will do that, as well. What's different
about ours is we encourage people to log their
weight daily for the reasons that we talked about earlier. And then you can also
track your food in the app. And honestly, I think our food
tracker is actually way easier to use than most
of them out there. What we typically get
great rave reviews about is how user-friendly
our interface is, that it makes intuitive sense. And so you track your food,
try to hit these macros that you're prescribed. And each week, you
will be prompted to check in with a coach
on your check-in day. And then you put in
some information. And then based on how
you're progressing, the app will adjust
or not adjust based on how you're progressing. So for example, if you're
hitting a weight-loss plateau, it will sense that. And it will reduce
your calories.

Or if you're trying
to gain weight and you've hit a plateau,
it'll increase your calories. And there's a lot of
back-end algorithm stuff that takes care of this. But the fundamental
crux of the app is we try to determine
your total daily energy expenditure because
that's going to tell us the first big thing
we need to know, which is, how many calories
do you need to be eating for your goal, right? So on the front
end, we basically do our best guess based
on your anthropometrics. It's not going to be perfect. But it'll get us
in the ballpark. And if you do know, like
some people already know, well, I know what I
maintain my body weight on, there's actually a spot where
you can manually enter that during the signup flow. So that's helpful for people
who are super nerds like me.

But then people will ask, well,
do you take Apple Watch data? Do you take this? Do you take that? And no, for the reasons
we talked about, that it overestimates
energy expenditure. What our app does is
it's an algebra equation. If you– because
your body weight, your maintenance calories
is your total daily energy expenditure. Your average calories that
you eat to maintain your body weight will be the same as your
total daily energy expenditure. So if we know how body
weight is changing and we know how many calories
the person is consuming, we can actually solve for
what energy expenditure is.

And you can see in
the app that we'll– there's a maintenance calorie
tracker, or energy expenditure tracker. And typically, after
about three to four weeks, even if the app
was off at first, it will have you pretty darn
close because, let's say somebody comes on. And their goal is to
lose a pound and a half a week or something like that. And the first week,
they lose 3 pounds. Now, the app actually
accounts for the fact that you can lose more
water weight the first week.

So they probably wouldn't
get an adjustment. But let's say the next
week, they lose 3 pounds. The app will sense that and
adjust their calories up because it will be estimating
that their energy expenditures are actually higher
than what it previously estimated based on the amount
of weight they're losing. And the same thing
goes in reverse. If they're not losing
the amount of weight that they're supposed
to, it will lower them based on the fact that it may
have overestimated their energy expenditure. But that's the first crux of
it, is tracking that energy expenditure. And then the next
thing is protein. So when the back-end
algorithm stuff is happening, calories are set first
based on your energy expenditure and your goal. So for example, if you're
on an aggressive diet, your calories are going to
be lower even if your energy expenditure might be a
little bit high, just because if you're trying to
lose 2 pounds a week, I mean, you're going to be in a pretty
aggressive calorie deficit. So it's going to set
the calories first. Then, it will set protein
based on your lean body mass.

Then, the calories
that are left over will be allotted to
carbohydrate and fat depending on your
dietary preference. And we have a few different
dietary preferences. There's balanced, which is about
50/50 to 60/40 carbohydrate to fat of the
remaining calories. Then you have low fat,
which is obviously a higher ratio of carbohydrates. You have low carb. You have a ketogenic diet,
which is very, very low carb. And then there's also
a plant-based option. And within each
of those options, still, you can go in and
actually shimmy the macros a little bit within
a certain range so that you can kind of dial
in what your specific dietary preference is
because, again, if we go back to what is going
to produce the best long-term results, it's whatever
the person can adhere to. So we really try to start
with the concept of adherence by allowing people to have the
dietary preference that they want.

And there's some other apps
out there that are good apps. For example, we get
asked a lot, what's the difference between our
app and the Renaissance Periodization app? And they have a great app. But theirs is kind
of more rigid. And it'll say, you're going
to eat this many meals. And you're going to have
these foods at these times. So we're kind of the opposite. We want to give you
maximum flexibility. Now, for some people, they
would prefer the rigid structure at first. But we find that
for most people, giving them more flexibility
typically improves adherence over the long run. So that's kind of
how the app works. And again, there's
multiple different goals. It's not just a weight-loss app. There's a maintenance. There's muscle-building. So you've got all kinds
of different goals that can be accommodated, different
rates of each of those goals.

And I mean, I've used the
app for over three years now to do my body weight. And I mean, when I say
that it's dialed me in– because I'm very regimented
with logging and logging my weight. So what I targeted to
weigh in at Worlds, I got down to the 0.1 kilogram. ANDREW HUBERMAN:
That's fantastic. LAYNE NORTON: So it
was pretty cool to be able to use a tool that I helped
develop to actually coach me. So it's a great tool. We did some statistics. We polled 2,500 members. And one of the
questions we asked is, would you recommend
this to a friend? And 91% said yes. So I think our average
retention is, like, seven months, which for an
app that costs $10 a month is really great. ANDREW HUBERMAN: That's great. Yeah, as I mentioned, a number
of people I know use it. This is not a paid promotion. But I think people need
guidance and tools.

And what we know about the
human brain is that winging it can work, but that the brain
will cheat itself often. There's a Feynman
quote about this. And I'll get it wrong. It's always bad to try
and quote Feynman anyway because he said
it so much better. But that we are the easiest– it's easy to fool
ourselves basically, is what he was saying–
easiest to fool ourselves. LAYNE NORTON: Absolutely. ANDREW HUBERMAN: Sounds great. We will put a link to it so
that people can check it out. Again, it sounds like a
wonderful tool and a tool that nets a lot of the
principles that sit as major themes for
weight loss, weight gain. I would assume directed
lean tissue gain is what most people are after,
and weight maintenance because a number of people
would like to just maintain. Listen, I really appreciate
your time and all that you're doing, certainly,
your time and energy and knowledge
today but also what you're doing on the various
social media channels. And just the fact that somebody
from the depths of academia is out there sharing
so much knowledge across so many
domains, you're a gem in this landscape
of nutrition and one that people really
need to hear from.

So thank you so
much for your time. LAYNE NORTON: Thank you. I appreciate the opportunity. I really enjoyed it. ANDREW HUBERMAN:
We'll do it again. Thank you for joining me today
for my discussion with Dr. Layne Norton. I hope you found it
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