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.

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 of today’s podcast.

Our first sponsor is Four Sigmatic.

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why would you want to put mushrooms in coffee?

First of all, let me tell you,

these are not psychedelic mushrooms,

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The coffee is delicious,

and you don’t taste mushrooms at all.

I know this because I’ve been using Four Sigmatic coffee

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As I’ve said before on this podcast,

I am not in ketosis, I’m not ketogenic.

I don’t advocate or follow any one particular diet.

For me, what works is to fast in the early part of the day

and to eat low carb and keto-ish throughout the day.

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This month, we’ve been talking all about hormones,

which are these absolutely incredible chemicals

in our brain and body.

They impact our entire lifespan.

So from the time that we are in the womb,

they’re controlling the development

of our brain and our bodies.

After we are born, they’re still controlling

the development of our brain and bodies.

And I did say development,

and that’s because contrary to what most people think,

development lasts the entire lifespan.

From the time you’re conceived until the time you die,

you are developing, you are changing,

and hormones are constantly updating and changing

the different functions of your body.

They have two major kinds of effects.

One are immediate effects, so they can actually bind to

or kind of park in parking spots on cells

and impact all sorts of things

like the growth of cells, et cetera.

They also can control gene expression.

This is the way that hormones during puberty

control body hair growth and breast development

and growth of muscles and limbs and height

and all sorts of things.

They are incredible.

We’ve talked about testosterone and estrogen.

We talked about insulin and glucagon

and some of the other things.

Today, we are going to talk about metabolism,

mainly going to talk about thyroid hormone

and growth hormone and some other related pathways.

I’m going to explain to you the logic

of how thyroid hormone and growth hormone work.

It will become obvious why I’ve paired thyroid

and growth hormone together in the same episode.

And I will, of course, talk about tools that you can use

to elevate or reduce thyroid hormone.

There are cases where people want to reduce thyroid hormone.

I will talk about tools that you can use

to elevate growth hormone.

There are rare cases where people want

to reduce growth hormone.

Most people are interested in increasing growth hormone.

So today is going to be rich with information,

rich with actionable tools.

And as always, the idea is to spell out

an organizational logic so you can come away

from this episode, and in fact, the entire month

on hormones, really understanding at some level

what these things we call hormones are and how they work.

And that’s really to arm you to encounter information

going forward, whether or not it comes from me

or from somebody else, a book or a course,

someplace else online, to make sense of how to work

with these incredible chemicals we call hormones.

Before we begin to talk about thyroid and growth hormone

and how our metabolism works

and how to control metabolism,

I want to answer a few questions that I received from you,

from the audience.

Every once in a while, someone will send me

a quite earnest question about something they saw

on the internet.

And one of the things I’ve heard about quite a bit

in the last couple of weeks is we’ve been talking

about hormones and food intake and how those interact

is this question of, are certain foods particularly good

for certain organs of the body?

And can that be predicted on the basis of the shape

of those foods?

So first of all, I want to acknowledge the question

as a valid one, because I see this every once in a while

out there, people will say, well, you know,

walnuts are in the shape of the brain

and therefore they are good for your brain,

or, you know, a particular fruit like the beet

often looks like a heart and it’s good for your heart.

And I certainly invite questions of all kinds

provided they are sincere questions.

However, I am not aware of any science whatsoever

supporting the idea that the shape of a given food

or object for that matter is relevant to its functional role

in the body in reference to biology.

Now, beets contain something

that we’re going to talk about today.

They contain a substance called arginine,

which actually can control the dilation

of blood vessels and arteries.

So it has some relationship to heart and heart health.

Walnuts contain various fatty acids that may be,

I want to underscore may be beneficial

for certain aspects of brain health,

but there’s no evidence whatsoever

that the shape of the food itself is relevant.

And, you know, I think what’s happened is,

is that people have gone out there and found foods

that contain certain substances like carrots

and vitamin A or walnuts and particular fatty acids

or beets and arginine, and they’ve selected the foods

that happen to be in the shape of the thing,

the organ that the particular substance like vitamin A

or fatty acids and so forth might benefit or support.

But of course, there are many, many other sources

of these nutrients that don’t come from walnuts

or from beets or from carrots.

And so I guess the short way to put it is that the idea

that the shape of some food is an indication

of whether or not that food would be healthy

for a particular organ in the body is absolutely unfounded.

I don’t know of any evidence for it.

And I’m not out to quash anybody’s great love

of these foods.

I enjoy all the foods I just described,

but the shape of things in the physical universe

bears very little, if any, relevance to the nutrients

that it contains and therefore the organs that it supports.

So thank you for your question.

But if you see that out there, I don’t even think you need

to tell the person who’s putting that information

out into the world.

I would just back away slowly.

One other thing before we move into today’s material.

Last episode, I talked about the problems with emulsifiers

in highly processed foods and the way that they can strip

the mucosal lining of the gut and they can limit

the signaling of hormones like CCK that can signal

to the brain satiety, the signal to stop eating.

And then we got into a discussion

about artificial sweeteners.

And I threw out stevia as an artificial sweetener

and several people reached out to correct me

that stevia is not an artificial sweetener.

It is a non-caloric sweetener and you are correct.

I lumped artificial and non-caloric sweeteners together.

And thanks to many of you that also sent me some references,

it does not appear that stevia can negatively impact

the gut microbiome.

It does seem unique among non-caloric sweeteners.

There are probably others out there.

The other thing that we discussed is how stevia can lead

to slight increases in blood glucose,

but can also improve insulin management just slightly,

probably cancels to zero in terms of its impact

on blood glucose provided it’s not at concentrations

that are super, super sweet.

Ingestion of anything that’s very sweet,

whether or not it contains calories or not,

artificial or not, will create an insulin response.

In fact, just walking past a bakery

and smelling delicious baked goods

can increase your insulin secretion.

And so I just want to point that out.

Thank you for the information and the references

that you found.

Please send additional ones if you do find them.

And I appreciate that you allow me to make corrections.

Every once in a while I misspeak here

and the opportunity to make corrections

keeps us all on the same page.

And please do keep any feedback that you have

about particular things I cover here coming my way.

There is so much interest in metabolism.

We hear about having a high or a low metabolism.

There are some people out there who would like

to reduce their metabolism.

They simply can’t eat enough to maintain their weight.

Most people, however, struggle with the opposite issue.

They struggle to maintain a healthy weight

and or their metabolism is too low.

Now there are a variety of reasons

why metabolism can be low.

Today we are going to talk about two hormones,

thyroid hormone and its related pathways

and growth hormone and its related pathways,

which arguably are the two hormones

and two systems in the body that are most significant

for setting your overall level of metabolism.

Before we dive into those,

I just want to cover a little bit of what metabolism is.

And I want to talk about which organs in your body

use the most energy.

So metabolism is the consumption of energy,

not necessarily eating,

but it’s the use of energy in the cells of the body

for growth of tissues, for repair of tissues,

and also just for day-to-day maintenance of function.

A good example of maintenance of function

would be your brain.

Most of your metabolic needs,

your so-called basal or resting metabolic needs

are for your brain, for thinking.

If you were to just sit in a bed all day

and do nothing but think,

that consumes about 75% of your metabolic needs.

Now there’s also moving around.

If you have a job that requires a lot of heavy labor

or lifting things, or you’re a new parent

and you’re carrying kids around

and you’re going up and down the stairs

and you’re back and forth to the refrigerator for formula,

et cetera, well, then you’re burning more energy,

burning more calories.

But even if you are very physically active,

unless you’re an ultra marathoner or a marathoner,

chances are that 75% of your metabolic needs

are coming just from your brain.

And that’s because neurons consume a lot of energy.

Neurons, of course, are just the nerve cells of your brain.

So these two hormones, thyroid hormone and growth hormone,

we think of as related to metabolism of things in the body,

keeping body fat low and keeping muscles strong

and tendons strong and repairing themselves, et cetera.

But they are also key for brain function,

for the ability to maintain cognitive function

throughout the lifespan.

So the big theme I’d like to introduce

is that metabolism isn’t just about losing weight,

but having a high metabolism,

provided it’s not too high, is great.

It means that you will have more lean tissue,

more bone and muscle, and less adipose tissue, fat.

And we know that that’s healthy.

How much fat and how much muscle?

Well, that varies,

and the numbers on this are always shifting.

But in general, muscle and its related tissues

burns more energy than does adipose tissue or fat.

And the water in your body doesn’t consume any energy.

So metabolism can be increased

simply by adding muscle to your body and reducing fat

or adjusting the ratio of the two.

But regardless,

even if you’re not interested in changing body composition,

these two hormones, thyroid hormone and growth hormone

are super important for metabolism of all kinds,

including tissue repair after injury,

including maintaining cognitive function and wellbeing

and the ability to think clearly as you age,

offsetting dementia and so forth.

So the big theme here really includes the previous episodes.

You don’t have to have seen those episodes,

but for the last three episodes and today as well,

we’ve been talking about hormones,

these substances that are released

from one location in the body

that go and act other locations in the body.

I’m going to tell you how that works

for thyroid and growth hormone.

But now that you’ve heard about testosterone and estrogen,

and you’re going to hear about thyroid and growth hormone,

I want you to realize that there’s a repeating logic.

First of all, there are neurons in your brain

in an area called the hypothalamus,

which it just means it’s below the thalamus hypo.

It sits at the base of your brain in the front,

it’s part of the forebrain.

So it’s more or less above the roof of your mouth,

maybe about a centimeter or so,

and then about a centimeter forward in most people.

And neurons in the hypothalamus

release hormones that are called releasing hormones.

So we’ve talked in previous episodes about, for instance,

gonadotropin releasing hormone.

So those are little neurons that then signal

another brain area called the pituitary

to release other hormones.

Today, we’re going to see this again.

In the brain, you have neurons

that release thyrotropin or thyroid releasing hormone.

You also have growth hormone releasing hormone.

So anytime you hear releasing,

chances are those are neurons that are in your brain

and they extend little wires,

we call axons, into your pituitary.

And the pituitary releases a bunch of hormones

into the bloodstream.

And the pituitary releases things

that most often have the name of stimulating hormone

because they stimulate organs.

So in keeping with the theme of thyroid hormone,

you have thyroid releasing hormone in the brain,

tells the pituitary to release thyroid stimulating hormone.

And then the thyroid, which we’ll talk about in a moment,

releases thyroid hormones.

In the testosterone and estrogen episode,

we talked about how you have gonadotropin releasing hormone.

There’s the releasing again up in the brain,

remember, releasing hormone comes from the brain.

Then you had things like luteinizing hormone

and follicle stimulating hormone,

which were in the pituitary

and those traveled to the ovaries or the testes

and acted on those tissues, okay?

So please try and embed this logic.

If you hear the word releasing hormone,

it’s coming from the brain

and that makes it actionable in certain ways

that we’ll return to later.

In addition, the pituitary is letting go

of all these hormones into the bloodstream

that are stimulating different tissues.

So for thyroid, it’s thyroid stimulating hormone,

and then it goes to the thyroid.

And the thyroid is a little butterfly shaped gland

that’s right around the Adam’s apple.

If you want to see yours,

not directly because it’s got skin over it,

what you would do is you’d take a sip of water,

you’d look in the mirror and you’d swallow.

And the thing that moves up and down, that is your thyroid.

Now, some people call it your Adam’s apple

because it sits right near this protrusion in the trachea,

which is the Adam’s apple.

No matter whether or not you’re male, female,

or regardless of what your chromosomal background is,

everyone has an Adam’s apple.

It tends to be more pronounced in people

that got a surge of testosterone early in development

because it has a testosterone sensitivity to it.

And that actually controls the timbre,

the so-called deepness of the voice.

So the thyroid gland sits right there

and it’s got four little bumps behind it

called the parathyroid gland.

And it releases two hormones into the blood

to stimulate different tissues and their metabolism.

And those hormones are called T4 and T3.

So if this is already sounding like a lot of information,

it’s really easy, I promise.

Releasing hormone comes to the brain,

stimulating hormone comes from the pituitary.

And in this case, we’re talking about the thyroid

binding up that stimulating hormone and saying,

oh, I need to release something that releases T4 and T3.

And guess what?

You can basically forget about T4.

T4, it’s not completely inactive.

It has some roles, but T3 is the one

that’s more or less active.

Now, what does thyroid hormone do?

A lot of people think, oh, thyroid, it’s like metabolism.

And people who are hypothyroid

all have bulging eyes and are real thin.

And people who have hypothyroid are overweight

and they have like, their eyes are like,

are, you know, half closed or something.

And indeed, thyroid hormone controls a lot of the features

of the face and the eyes and it can control amounts

of adipose tissue and so forth.

But the main role of thyroid hormone of T3

is to promote metabolism.

And that doesn’t just mean the consumption of energy,

it means the utilization of energy,

including the buildup of tissues.

So it acts on all sorts of target tissues in the body.

It acts on muscle, it acts on the liver,

it acts on the cartilage, it acts on the bone.

And it’s not just involved in using energy,

it’s also converting energy.

I do realize I said that twice.

It’s involved in taking fats

and breaking them down into fatty acids

and converting those into ATP,

which is an important thing for cells to use energy.

It’s also involved in taking sugars

and turning those into energy.

And yes, it goes to adipose tissue to fat.

We have different kinds of fat that we’ll talk about today,

but it goes to white fat and it liberates

or helps liberate some of the fats from those fat cells

and use them for energy.

And this is why higher thyroid

is associated with leaner bodies.

Lower thyroid is associated with less lean bodies.

So one thing that’s absolutely key and is actionable,

we’re right there already in discussing tools is iodine.

Iodine comes from things in the ocean, right?

And here are a couple of interesting facts about iodine.

And then we’ll talk about whether or not

you should be supplementing iodine or not.

First of all, iodine is most common in sea salt,

in kelp and in seaweed.

And most people can get enough iodine

from the food they eat and or the table salt they consume.

Almost all table salt from all over the world,

regardless of where you are, contains iodine.

The thyroid needs iodine in order to produce thyroid hormone

and you need sufficient levels of thyroid hormone,

not too much, but you need it.

So chances are you are getting enough iodine,

although you might not,

especially those of you following a particularly

quote unquote clean diet might not be getting enough iodine.

Here’s the deal with iodine.

Iodine combines with an amino acid

that we’ve talked about before called L-tyrosine.

L-tyrosine comes from meat, from nuts.

There are some plant-based sources as well.

It is the precursor to dopamine.

But in the thyroid, iodine combines or works with L-tyrosine

to produce T3 and T4, the thyroid hormone.

So you absolutely need sufficient iodine.

You need sufficient L-tyrosine.

And then you also need something else,

which is called selenium.

And we’ll talk about selenium in a moment.

So there’s a condition that shows up

in little pockets in the world.

It’s not super common,

meaning it’s not very widespread,

but in certain areas that are far away from the ocean,

at one point this was historically

in the Midwestern states of the United States,

in some mountain regions of other countries,

in some areas of Africa that were far from the ocean,

people would get extremely swollen bulges in their necks.

And this was called goiter.

And the reason they were getting those swollen bulges

is because the thyroid itself was hypertrophying.

It was growing in an attempt to churn out more thyroid,

and because it was getting a lot of stimulating hormone

from the pituitary.

But, and I don’t want to go too far off track here,

but as you recall,

the brain and the pituitary are paying attention

in a cellular sense to the levels of hormones in the blood.

And when those hormones get too high,

they shut off the stimulating hormone.

They shut down the signal to make more,

kind of like a thermostat.

When the levels are too low,

like there’s not enough testosterone in the bloodstream,

or there’s not enough estrogen,

the brain will continue to push out the signal to make more.

Similarly, if there’s not enough thyroid circulating,

or there’s not enough iodine to make thyroid,

therefore not enough thyroid hormone circulating,

the thyroid gland itself is not getting shut down.

There’s tons of stimulating hormone and releasing hormone

coming from the brain, like release, release, release.

And there’s no way they can make thyroid hormone

instead the gland just gets bigger and bigger and bigger.

And so people get goiter.

This is one of the reasons why table salt has iodine in it.

Although there are other foods

that have iodine in it as well.

So how much iodine do you need?

Well, you don’t need a whole lot.

Some people who are hypothyroidal might,

and I want to emphasize might,

you absolutely should talk to your doctor.

This is a serious matter.

Anytime you’re talking about hormones

or manipulating levels of thyroid,

you absolutely want to talk to your doctor.

Some people benefit from supplementing iodine.

It is contained in most salts.

It’s in Himalayan salt, not always, but often.

I know these days there’s a lot of excitement

about pink salts and sea salts,

and the kind of artisan salt thing

has kind of taken off in the foodie land, which is great.

Some of them are actually quite tasty.

You can just take it directly if you like the taste of salt.

But iodine can be supplemented through things like kelp

and seaweed and kelp tablets.

Now, if you are hyperthyroidal, you make too much thyroid,

that actually can be a problem.

So really the best way to figure this out

is to get your blood levels tested of thyroid hormone.

But there’s so much iodine in the ocean

that believe it or not, people that live near the coast

can actually just absorb it through the air

just by breathing ocean air.

So that gives you a sense of just how little iodine

you actually need to consume in food or in salt.

So if you’re within a few miles of the ocean

or you visit the ocean from time to time,

you’re probably getting plenty.

It does have to come together, as I mentioned,

with L-tyrosine, and this is why foods

that contain L-tyrosine,

and provided that you have sufficient iodine in your diet,

and if you have sufficient selenium in your diet,

does serve to increase your metabolism.

And that is, again, is for the growth and repair of tissues.

And that’s really important.

It’s not just about keeping your metabolism high

so that you can be on the leaner side of things

or adjust your body weight, excuse me,

your body composition ratios the way you like.

Repair of injuries, repair of brain tissue,

clearance of any damage from neurons,

clearance of any damage to the body

is also going to depend on thyroid.

Again, metabolism being this kind of rate

of fuel consumption and use in the body generally,

not just about body mass indexes and things of that sort.

So let’s talk about selenium because it’s really important.

And even though most people are getting

a lot of sufficient iodine,

and most people are probably getting enough L-tyrosine,

I’m guessing most people may not be getting enough selenium

if their goal is to increase thyroid hormone,

at least that’s what the literature says.

Without going into the biochemistry,

selenium is important in order for thyroid hormone

to be made because of the way that it allows L-tyrosine

and iodine to interact.

And the thing is, most people aren’t getting enough selenium

because they don’t eat foods that are high in selenium.

Now, how much selenium you need

will depend on where you live.

It actually varies country by country.

Some countries I found say that you should get

a hundred micrograms, some say 200, some say 155.

The average was about 155 micrograms,

the countries I looked at.

People who are trying to increase thyroid levels

might want to consume more selenium.

And if you consume a vitamin, of course,

you want to make sure if it has selenium

that you’re not overdoing it by consuming

a lot of selenium rich foods either.

But nonetheless, I think it’s fair to say

that most people probably could do well

by ingesting slightly more selenium

than they currently are.

Although, of course, always talk to your doctor.

Brazil nuts are the heavyweight champion of foods

to get selenium from.

It has very high concentrations of selenium.

In just six or eight, Brazil nuts contain something

like 550 micrograms of selenium.

It’s also present in fish.

So certain fish like yellowfin tuna,

although nowadays, whenever I mentioned tuna or shellfish,

which is the other rich source of selenium,

people will tell me immediately,

there are all sorts of issues around farm,

not farmed, mercury, et cetera.

So I’ve never particularly liked eating fish

because of the way it tastes.

So that’s why I avoid it.

But for those of you that like it,

I’m sure you’re much more skilled in knowing

which fish to buy and which fish not to buy.

Ham, of all things, contains a lot of selenium.

For whatever reason, pork does.

I’m not a big consumer of pork.

Beef has some selenium.

But what’s interesting, if you look at the sources,

pork, beef, turkey, chicken, cottage cheese,

eggs, brown rice, what you want to understand

is that Brazil nuts, six to eight Brazil nuts,

has 550 micrograms of selenium.

And all the other foods I mentioned,

at much greater portion size than equivalent

to six or eight Brazil nuts,

either by volume or by calories,

they have something like 30 to 50 micrograms of selenium.

So if you’re not eating Brazil nuts,

and I’m guessing most people aren’t,

and you’re not eating a lot of animal-based foods,

which I know many of you aren’t,

then you’re probably not getting enough selenium.

And again, you can have these levels measured

or you can just check what you’re consuming

and figure out whether or not you’re meeting

the ration that you need in order

to get healthy levels of thyroid.

It is present in things like mushrooms,

but again, in a bowl of mushrooms,

what is the equivalent to a bowl of mushrooms?

12 micrograms of selenium.

And if the daily ration is something

in the 100 to 200 range,

again, look it up for the area you are,

you can see really quickly why,

even though things like mushrooms and spinach

and milk and yogurt and lentils and cashews,

so now we’re into the vegetarian segment

of the list that I constructed,

you’re probably not getting enough selenium.

So it’s kind of an interesting thing

if you’re an experimenter

and you get the clearance from your doctor,

you could try increasing your selenium levels

and see how that impacts your metabolism.

Again, Brazil nuts are probably going to be

the most direct way to get sufficient selenium levels,

but because levels are so high in Brazil nuts,

it also means that you could overdo it as well.

I’m not really aware of what the consequences are

of getting too much selenium,

although you can get too much of anything

and I’m guessing those consequences aren’t good.

I also want to mention that for children,

their daily requirements of selenium are much lower,

as low as 30 or 40 micrograms for kids 14 years or younger.

And in some areas, I really want to underscore this,

the amount of selenium that’s recommended daily

is as low as 55 micrograms.

So it’s not that you should be shooting for thousands

or even high levels of hundreds of micrograms of selenium,

and again, that’s micrograms, not milligrams.

So again, look into what you need,

but if you’re somebody who’s interested

in keeping thyroid function healthy and productive,

then you certainly want to make sure

you’re getting enough iodine,

you’re getting enough selenium,

and you’re getting enough L-tyrosine.

And it’s interesting when you start looking

at the various foods, especially highly processed foods,

then you start to realize that perhaps many people,

maybe you are not.

Not incidentally, selenium has some other effects on health

that can be quite positive.

And even though these don’t relate to thyroid

or growth hormone function specifically,

I think you might want to know about them

given that we’re on the topic of selenium.

The first is that there are three studies,

all of which showed very high efficacy

for reducing the risk of something called preeclampsia.

Preeclampsia is seizures that are related

to blood pressure issues during

or around the delivery of a new baby.

And it actually, it’s a rare-ish condition,

but it actually can be quite deadly.

And so the fact that selenium is important

for offsetting preeclampsia risk is interesting.

I don’t know the exact mechanism,

and I’m guessing there are only a few of you out there

that are either pregnant or thinking of conceiving soon,

but that’s worth noting.

Obviously, anything related to pregnancy or lactation,

especially talk to your doctor.

I’m guessing that selenium is probably

in a lot of prenatal formulas,

but that’s one clear benefit of having sufficient selenium.

The other is a reduced prostate cancer risk.

There’s a study showing that having sufficient selenium

can reduce prostate cancer risk.

And there is some evidence that if you consume foods

from areas with soil that’s low in selenium,

that can be a problem.

And last episode, we talked about all these issues

related to soil quality,

things that are making their way into food

that are disrupting hormones and so forth.

But having sufficient selenium from food

could offset the low content in any soil.

And so that apparently can reduce prostate cancer risk.

It’s a minor effect,

but it’s a statistically significant one.

And the other one is a reduction in acne,

which is interesting.

I’m guessing that that probably has to do

with the thyroid hormone pathway

because of the way thyroid hormone can impact the liver.

And it turns out that the liver

and various biochemical reactions in the liver

can impact acne.

And that’s probably an episode all into itself,

but those are just some additional benefits

of getting sufficient selenium.

Okay, so we’re already deep into tools

related to making sure that you have sufficient selenium,

iodine, and L-tyrosine in order to make enough

thyroid hormones that can support your metabolic processes

in your liver, your muscles, your tendons,

for whatever purpose, keeping your metabolism high

for body composition reasons or for healing,

for keeping your brain working well.

Earlier, I mentioned there are people

who are following very clean diets.

So these are people that consume no processed foods.

You know, any starch they might eat

is going to be maybe a rice or a grain,

or any protein they might consume

is going to be either from, let’s hope,

from humanely raised animal sources

or maybe they’re pure plant-based.

Believe it or not, those folks are actually

very susceptible to low iodine

because it turns out that diets that are very meat-rich

and don’t have many vegetables,

as well as diets that are very vegetable-rich

but don’t have many meats or salts

are at risk of lowering thyroid hormone

by way of the iodine pathway and other pathways.

And so let me try and simplify this for you.

Chances are, if people are doing the all-meat diet,

they’re not sprinkling,

they’re not wrapping those steaks in seaweed

and they may or may not be supplementing with iodine.

Chances are they’re probably consuming iodine salt,

but their requirements go up

if they’re not consuming vegetables.

People who are consuming vegetables,

it’s kind of interesting,

we always hear that we should have

our cruciferous vegetables and those are so important,

but they’re actually substances, compounds,

within high-quality cruciferous vegetables

that can interfere with thyroid hormone function.

So if you’re eating a lot of that stuff,

a lot of cabbages and just look up your other,

I think broccoli is a cruciferous vegetable

and I won’t read off the whole list,

you could just put into the internet.

But we’re always told to eat

a lot of the dark leafy green stuff.

Well, unless that dark leafy green stuff is kelp or seaweed,

chances are that we’re not getting enough iodine.

Unless we’re adding salt to our food.

And chances are that we may be lowering

the total amount of thyroid that we’re making,

as well as the fact that in plant-rich diets,

it’s hard to get enough L-tyrosine.

And I don’t want, you know,

I’m not here to inflame any of the vegans

or the carnivore folks.

I don’t take a stance either way on any of that.

I’m just learning, trying to report the science.

The point I want to make is your health is important.

So if you are purely plant-based

and you’re eating a lot of cruciferous vegetables,

make sure you’re getting enough iodine.

It does seem like the cruciferous vegetables

can increase the need for further iodine.

And same thing if you’re purely,

you’re on this all meat diet or you’re keto

and you’re not ingesting many vegetables.

So I always thought that the cleaner the diet, the better,

but it turns and probably that’s true

from the standpoint of, you know, hormone regulation,

you know, estrogen and testosterone and other hormones,

the highly processed foods really are terrible.

There’s so much evidence for that.

The phthalates in plastics and the processed foods

and the emulsifiers,

all the stuff we talked about previous episode.

But it does seem to be that people

that are not getting enough iodine for whatever reason

really need to check out whether or not

their iodine levels need to be increased

because of the fact that they’re consuming so many plants

or so many meats and in some cases,

plants that actually lower thyroid hormone.

And not to beat a dead horse or cabbage,

but there are a number of things that iodine can do

that are positive, that are sort of,

they’re related to thyroid, not directly.

They’re kind of offshoots of the thyroid pathway

on their downstream of it, we would say,

in terms of how they impact metabolic function.

One of those is to reduce something

called C-reactive protein.

Some of you may have heard of CRP or C-reactive protein.

C-reactive protein is something that you want to keep

at modestly low levels.

It’s associated with inflammation

and various forms of heart disease and even eye disease,

macular degeneration.

So it does appear that iodine supplementation

or getting sufficient iodine from food either works,

is associated with reduced levels of C-reactive protein

in the blood and an anti-inflammatory effect.

And the anti-inflammatory effect brings us back

to our old friend interleukin-6.

Remember, there are these inflammatory cytokines.

They have many, many names

because there are many, many of them.

Interleukin-10 is the one that’s anti-inflammatory.

Interleukin-6 is the one that’s inflammatory.

Anytime you see IL-6,

that usually means that there’s an inflammatory response.

There’s a wound, there’s inflammation of the brain.

Somebody is either sleep deprived or had a brain injury

or they’re dealing with some sort of infection.

IL-6 is kind of a catch-all for inflammation.

And it does appear that iodine supplementation

can reduce circulating IL-6

associated with inflammation.

So in that sense,

iodine can have an anti-inflammatory effect.

So by now it should be abundantly clear

if you care about thyroid hormone,

if you care about the pathways that it impacts,

like having a high level of metabolism,

which I guess if for no other reason is attractive

because then you can eat more

and still maintain a healthy body composition,

but also for brain health, cognitive function,

tissue repair, all that stuff,

keeping C-reactive protein low, keeping IL-6 low,

make sure you’re getting enough iodine,

selenium, and L-tyrosine.

If you’re curious how thyroid actually increases metabolism,

allows you to eat more, et cetera,

it relates to something we covered last issue,

which is glucose.

Remember when you eat something, blood sugar goes up,

insulin is secreted from the pancreas

and it makes sure that blood glucose doesn’t go too high,

which can damage tissues or too low,

which can make you hypoglycemic.

Thyroid increases glucose uptake by various tissues,

in particular muscle and bone.

It actually can increase bone mineral density,

which is a really good thing as you get older.

Injuries, when I say older, I mean basically 30 and older.

The reason you can recover more quickly from injuries

if you have a healthy thyroid and healthy thyroid pathways

is because you can consume energy,

that energy is diverted toward bone repair

and muscle repair and cartilage repair.

And so the way it does this again is by increasing ATP,

but the whole idea here is that iodine, selenium,

l-tyrosine allow thyroid to be at healthy levels

so that thyroid then can take glucose in the blood

and divert it to tissues for it to be used,

in particular your brain.

And that’s why these things that we’re talking about,

supplementing or getting from food

can actually improve or support brain function.

People are always asking me,

what is the food that I should eat for my brain?

Like, are blueberries good for your brain?

They do ask me, are walnuts good for your brain?

Because it looks like a brain.

We talked about that earlier.

The fact of the matter is that what you need

are nutrients that support hormones

and biological pathways that support the brain.

That’s the way to think about it.

And I realized when people ask,

what should I eat to support my brain?

That’s basically what they’re asking in short form.

So keeping your thyroid hormone healthy,

at healthy levels that is,

is going to be terrific for your brain

because 75% of your metabolism is from your brain.

The ability of your brain to use glucose

or ketones for that matter is going to be aided

by having healthy thyroid.

So do the things, take the things,

eat the things that are going to allow you

to have healthy levels of thyroid hormone.

I’m sure a number of you are out there wondering,

do I have healthy levels of thyroid hormone?

Those can be measured from the blood.

There’s some telltale signs of having really high thyroid

or really low thyroid.

And I could start listing those off.

They’re easy to find online as well.

Things like bulging eyes, inability to maintain weight,

shaky, anxiety, that’s kind of hyperthyroidal,

thinning of hair, this kind of thing.

I don’t want to get into diagnosing hypothyroidism

and hyperthyroidism.

It’s just impossible because you’re there and I’m here

and we’re kind of shouting back and forth

through a tunnel of video and comments.

If you’re concerned about having excessively high

or excessively low levels of thyroid hormone,

absolutely look up what the symptoms are.

Talk to your physician.

And there are a number of good treatments.

I didn’t talk about prescription drugs

that can improve symptoms related to hypo or hyperthyroid.

Of course, they have synthesized thyroid.

So if you don’t make enough thyroid, you can take thyroid.

It’s by prescription.

If you have too much thyroid,

sometimes they’ll take out the thyroid gland

or they can administer drugs that will either block

receptors or will interfere with some of the pathways

from the brain to the pituitary

or from the pituitary to the thyroid

in order to adjust thyroid hormone that way.

So there are the big guns in terms of the treatments

for different thyroid disorders,

but we’re not talking about thyroid disorders.

We’re talking about how to get and maintain thyroid levels

in healthy ranges and some straightforward ways to do that

through diet and supplementation.

There’s also a lot of evidence

that for people who menstruate,

levels of thyroid hormone can fluctuate dramatically

across the menstrual cycle.

So that’s really going to be a process of experimentation.

I don’t know that you could, in theory,

take blood at different phases of your cycle

and figure out whether or not your thyroid hormone

was excessively high or low at different phases of the cycle.

That’s going to be pretty tough to do.

If you have an endocrinologist

that’s willing to do that with you, terrific.

I think most people are going to have to figure out

how supplementing the sorts of things

that we talked about before or getting them from foods

relates to different aspects of their cycle.

In general, the first half of the cycle before ovulation,

people crave carbohydrates and sweets more related to the,

and that makes total sense

based on the biology of the menstrual cycle.

Thyroid hormone is going to go up as you, as anyone,

male or female, menstruating or not,

increases more starchy carbohydrates.

This is interesting because ketogenic diets

have been shown to slightly lower thyroid levels.

And that makes sense because in ketogenic diets,

blood glucose levels are very low

and thyroid hormone is secreted in large part

in proportion to how much glucose is in the bloodstream

and how much that glucose, excuse me,

needs to be regulated.

So I’m not trying to demonize the ketogenic diet.

I think it definitely has its place.

There are 22 studies now

showing that it can dramatically reduce blood glucose.

And about a third of those show

that thyroid hormone levels are slightly reduced,

sometimes significantly, if not more,

in the ketogenic diet.

That may explain, I want to highlight may explain the fact

that when people go back to a more traditional diet,

if they’ve been on a ketogenic diet for a long time,

that oftentimes they will gain weight very quickly

as they bring carbohydrates back into their diet.

Some people are cycling between ketogenic

and non-ketogenic every three, four days,

so-called cyclic ketogenic diet.

Some people are staying ketogenic for long periods of time.

Some people, six days on, one day off.

So there’s a huge variation there.

The point is that carbohydrates,

starchy carbohydrates in particular,

support the healthy production of T3 and T4.

And so if you’re very low carbohydrate,

you’re going to have a reduction in T3 and T4.

And so if you’re going to bring carbohydrates

back into your diet,

then you might want to do it more gradually.

And for those of you that menstruate

and are craving carbohydrates

in the early part of the cycle,

that is actually associated with having a healthy cycle.

If any of you have had a healthy cycle on a ketogenic diet,

that would be interesting.

Maybe let me know through the comments

or point me in the direction of some research

if you’re aware of it.

So as you can start to see,

there’s this really beautiful interplay

between the different hormones,

between insulin and glucose,

between estrogen and thyroid,

between thyroid and blood glucose and the ketogenic diets.

It all starts to fit together

in ways that make a lot of sense once you understand

the core elements of what the hormones are

and the variety of tissues that they work on.

The simple version of this is

if you haven’t had a carbohydrate for a year,

then your T3, T4 levels are going to be pretty low.

And I’m sure there’s some ketonistas out there

that are going to say,

wait, no thyroid hormone levels go up with keto.

That might be true for other reasons,

indirect reasons related to hormone pathways

that cascade from being in ketosis

for long periods of time, great.

But for most people

that don’t consume any carbohydrate,

T3, T4 are going to go down.

And when they start to consume foods

that require thyroid metabolism

in order to work with, to metabolize,

then weight gain can sometimes happen more quickly.

So it’s just something to consider

and it’s something to work with carefully

if you’re going to be cyclic ketogenic,

long-term ketogenic.

And if you’re not ketogenic

and you’re consuming carbohydrates

and the three things that we talked about earlier,

selenium, tyrosine, and iodine,

chances are, unless there’s an underlying condition there,

that your levels of thyroid

are going to be in healthy range.

Next, we’re going to talk about growth hormone.

Growth hormone has received a ton of attention

in the last 20 years.

I actually remember when it was first sequenced.

This was a huge deal.

There was a huge patent drama.

I won’t mention the universities or the people involved.

There were companies and monster patents and payouts.

And it was really interesting.

You can look that up online

if you’re interested in some of the scientific history.

Growth hormone is a pretty straightforward one

for you to understand now

because it follows the exact same logic as thyroid hormone.

In fact, their functions are so closely overlapping

on the, you know, when we first look at the face of it

that you’re probably going to think,

why do you have these two systems?

So just very briefly, growth hormone releasing hormone.

So remember, releasing means it comes from the brain,

comes from the brain and tells the pituitary

to release growth hormone.

And then growth hormone is released into the bloodstream

where it goes and acts on a ton of tissues,

muscle, ligaments, bone, fat, et cetera,

to increase metabolism.

It sounds just like thyroid hormone

and they do work in parallel.

And that’s why we’ve lumped them together

in the same episode.

They increase metabolism and repair and growth of tissues.

A conversation about growth hormone would be incomplete

if we didn’t talk about the kind of extremes.

There are certain people who are born

that don’t make enough growth hormone

and they end up very short in stature.

There are certain people who make a ton of growth hormone

and they end up very, very large.

They tend to have very large appendages.

They have something called acromegaly.

It’s kind of like a ridging of the forehead.

It’s actually a bone ridge.

They are giant and it used to be called giantism.

And most people, of course, are in a range of height

and appendage length that doesn’t imply

that there’s a growth hormone disruption there.

Growth hormone received a lot of attention

after it was sequenced because that meant the opportunity

to inject growth hormone

and replace growth hormone that was lost.

And there was actually a lot of cases

of people taking their kids

and trying to get them to be taller for whatever reason

by injecting growth hormone.

Today, we’re going to talk about the things

that anyone can do to increase growth hormone.

And there are reasons why certain people

would want to do that.

People who overproduce growth hormone

certainly would not want to do that.

People who underproduce it would probably want to do that.

People that make normal, quote unquote,

levels of growth hormone might want to do that as they age

because during puberty and development,

the pituitary is churning out tons of growth hormone.

It’s responsible for the growth, not surprising,

of the body and all its features,

height just being one of those.

And so as we age, we make less growth hormone.

And that is one of the reasons

why we recover more slowly from injuries.

It’s one of the reasons why we accumulate body fat.

And it’s one of the reasons why our metabolism slows.

And so growth hormone replacement therapy

has been tremendously popular in the last 20 years,

which is not to say it doesn’t carry its problems, it does.

Here’s one of the major problems

with injecting growth hormone.

Not saying people shouldn’t do this.

If the doctor has approved it

or it’s in keeping with their particular life goals,

but growth hormone, if it’s in levels that are too high,

will cause growth of all tissues.

So not just muscle, not just reduction in body fat

by metabolizing, you know,

by allowing fatty acids to be pulled out of storage

and used for ATP,

but it will also cause increase in growth of the heart

and the lungs and the liver and the spleen.

And so this is the concern with abuse of growth hormone.

So we’re not going to be talking

about abuse of growth hormone.

We will, however, talk about tools that anyone can use

to increase levels of growth hormone.

Some of them are behavioral,

some of them are supplement based,

and some of them interact with behaviors and supplements.

And what’s cool about the discussion about growth hormone

is that the tools that exist out there

to increase growth hormone are very actionable.

Most people can do these

without the need for any equipment or even any supplement,

although there are some supplement related themes

for tools for growth hormone increase.

And also the increases that one can get

in growth hormone are substantial.

So normally when you talk about the difference

between taking something as an exogenous substance

like testosterone or estrogen

versus using supplements or behaviors to increase them,

you’re talking about tenfold differences

from, you know, administering the prescription compound.

In terms of growth hormone,

there are things that can increase growth hormone

three, four, 500% or more.

And even though that’s a short-lived increase,

they can have very powerful effects on metabolism

and on repair of tissues.

So let’s talk about those.

Okay, let’s go step-by-step

in terms of the things that anyone,

perhaps everyone should be doing

in order to maintain healthy growth hormone levels

or increase growth hormone levels.

Unless you have overproduction of growth hormone,

chances are these things are going to benefit you.

However, as always, I want to emphasize,

talk to a doctor before you do anything,

including remove any treatments.

So anything you would add or take away,

that’s responsibility of you and your healthcare provider.

Okay, I don’t just say that to protect me,

I say that to protect you.

First of all, growth hormone is released every night

when you go to sleep.

And it’s released in the early part of sleep

during so-called slow-wave sleep.

So the two conditions that have to be met

in order for growth hormone to be secreted regularly

for tissue repair, et cetera,

are you need to get into slow-wave sleep,

the so-called deep sleep,

and you need blood insulin and glucose to be relatively low.

So eating within two hours of sleep, excuse me,

eating within two hours of going to sleep

is going to suppress growth hormone release.

That’s very clear.

However, some people are going to have problems

falling asleep if they are too hungry.

So you have to work with that

and decide what you’re going to eat

and when you’re going to eat that thing

so that you’re not so hungry

that you’re having trouble falling asleep.

The episodes on sleep that were covered

in episodes two, three, and four of the Huberman Lab Podcast

has, I believe, more tools there

than you could ever want or make use of

in terms of how to optimize sleep.

So you can refer to those if you like.

So don’t eat too close to sleep

and then get into slow-wave sleep.

And as I talked about in one of those earlier episodes,

the first half of the night,

slow-wave sleep and deep sleep predominate.

The second half of the night, it’s another kind of sleep.

We call REM sleep.

So what is special about this early phase of sleep?

This is how you should be thinking

if you listen to this podcast.

You should be thinking, okay,

I hear that something is important, it’s related,

it’s in the pathway, but mechanistically,

when we say get into slow-wave sleep,

get into deep sleep,

that’s when growth hormone is secreted.

The question you should be asking yourselves

as scientists of yourselves is, wait, why slow-wave sleep?

What in particular about slow-wave deep sleep

allows the pituitary to release growth hormone?

Like, what is it?

Because if you can understand that,

if you can understand a little bit of mechanism,

there are actually ways that you can increase the amount

of growth hormone that you release

both in sleep and out of sleep.

So the answer is, it’s a delta wave activity in the brain.

Delta waves are these big giant waves of activity

in the brain that correlate with slow-wave sleep

as opposed to faster waves of activity

that associate with rapid eye movement sleep.

So slow-wave sleep and the delta activity

actually triggers the neurons in the brain,

the releasing hormone, right?

Growth hormone releasing hormone neurons

to signal to the pituitary.

Now, how do I know this is true?

And what can you do with this?

Well, we know this is true because researchers

have taken people in sleep deprived them

and they’ve just asked, well,

is it just one period of time every 24 hours?

And then the pituitary releases growth hormone.

If that were the case,

that would say that growth hormone is just released

in a so-called circadian dependent way.

Every 24 hours, there’s the pulse of it.

But no, it’s always relating to slow-wave deep sleep

and delta waves.

And this is cool because what it means is that

even if you’re not measuring your brainwaves during sleep,

which most of you probably are not,

you might be measuring slow-wave sleep or deep sleep

using a device like a whoop or an aura.

And even if you’re not,

what this means is that during the day,

there’s the potential to also increase

growth hormone release if you can get the brain

into the so-called delta waves.

And it turns out there are things you can do in waking

as well to increase growth hormone release.

So we’re going to talk about those next,

but as a tool and to just really make sure

that we put brackets around this,

try and have blood glucose not too high.

So if you do need to eat close to bed,

you wouldn’t want to eat anything

that would increase blood glucose too much.

Try and not eat too close to bedtime.

Get into deep sleep early in the night,

get the growth hormone release,

and understand that it’s the delta waves of activity,

these sweeping big waves of activity in the neurons

that stimulate the brain to stimulate the pituitary.

Because once you understand that,

then you have something to anchor to in terms of thinking,

what are the things I can do in waking

that will allow me to release more growth hormone,

which for most people is going to be a good thing.

Several times before on this podcast,

I’ve talked about the fact that I’m not a big fan

of melatonin supplementation for most purposes.

It might be helpful under conditions of jet lag.

However, there are a lot of reasons

why I personally don’t like melatonin.

It interacts with the reproductive hormones,

testosterone and estrogen,

and that whole axis in ways that are unattractive,

at least to me, it suppresses puberty during development.

It’s present in much, much higher doses in most supplements

than one would normally make, like 100-fold, 300-fold.

However, today I’m going to talk about an instance

where very low levels of melatonin supplementation

might actually be advantageous.

And that is aiding the transition

to the delta wave, slow wave sleep I just described,

because that’s the pattern of sleep

and brainwave activity that triggers growth hormone release.

So whereas most melatonin supplements

are one milligram, three milligrams, 12 milligrams,

this kind of thing, that is supraphysiological.

There are some data showing that microgram,

maybe 500 micrograms of melatonin, so half a milligram,

can be beneficial in shifting the pattern

of early night sleep

toward more of the slow wave deep sleep delta activity

and improving growth hormone release.

Not a lot of studies, but the ones that I saw are quality.

They were done in subjects that, you know,

both sexes, sufficient numbers, et cetera.

So this is interesting.

So if you’re interested in melatonin supplementation,

you might think about it just at very low levels,

you know, hundreds of micrograms

as opposed to the milligram dosages.

Most of the ones out there

are going to be in milligram dosages.

So that’s one way that some studies have shown

that you can increase the amount of growth hormone

that’s secreted in early phases of sleep.

Now, the delta wave activity

and the slow wave activity in the brain

being very important for growth hormone release

and growth hormone release being so important

for metabolic functions and peeling away unwanted body fat

and repairing tissues, et cetera,

forces us to ask, well, what other things can we do

in waking in order to increase growth hormone release?

So let’s start with the ones that have

a potentially big effect,

but are a little bit harder to access.

And for that, I want to point toward a book,

which is really kind of interesting.

It’s not focused on growth hormone,

but the book is called Altered Traits.

This is the book.

It’s an excellent book.

Altered Traits by Goldman and Davidson,

Science Reveals How Meditation Changes

Your Mind, Brain and Body.

Very interesting book.

For those of you that are interested in meditation

and perhaps those of you who are not,

but are considering it,

what they talk about in this book is the fact

that meditation has two separate lines of effects.

One of those lines of effects

are things that change your state.

So you’re stressed, you sit down, you meditate

and you relax and you go into a particular state.

The other are the changes that occur over time

and those are changes in trait.

So personality can actually change

with long bouts of TM meditation or repeated meditation.

In any case, the reason we’re talking

about altered traits today is because certain types

of meditation can get people’s brains into states

that very closely mimic slow wave sleep.

If you hear snoring in the background,

Costello sounds like he’s in slow wave sleep.

He’s big oscillatory snores that he’s in 23.6 hours per day.

So what this means is for people that are interested

in increasing growth hormone, a meditation practice

that allows you to get into these slow wave

delta type frequency activity in the brain

may be very beneficial because as I mentioned before,

that’s what’s gating growth hormone release.

It’s not just a circadian phenomenon,

it’s actually controlled by these brainwaves.

I did look up binaural beats.

I get so many questions about binaural beats

and it’s a really attractive idea, right?

Binaural beats, for those of you who don’t know,

you listen to one frequency of tone in one ear

and another frequency of tone in the other ear.

And then the brain essentially takes the average of the two

or there’s some other wiring in the brainstem

that makes it not quite the average,

but takes the average of the two for sake of discussion.

And that frequency is what the brain entrains

or maps onto.

There are a lot of apps that are claiming

that you can get the brain into delta waves

using binaural beats.

I could not find quality peer review studies supporting that,

but I know there are a lot of fans out there

of binaural beats.

If you know of any literature that’s independent

of the company that makes the binaural beat technology,

so Unbiased Research, please send it my way.

But in Altered Traits, Goldman and Davidson talk about

the fact that people who do 20 minutes

of sitting meditation per day

can access these slow wave sleep-like brain states.

Now, I’ve talked a lot on here about non-sleep deep rest,

things like yoga nidra and hypnosis.

I’m not aware that those will put people

into slow wave sleep per se or delta waves per se.

So we’re really talking about 20 minutes

of more traditional type meditation.

Okay, so we talked about very low doses of melatonin

as a way to trigger delta waves

and more growth hormone release in sleep.

There’s science to support that.

We’ve now talked about a waking behavior of 20 minutes

of sort of what I would call standard meditation

or just sitting there concentrating on one’s breathing

to try and access delta waves.

Binaural beats, no science yet.

Who knows, maybe there’s science to support it.

If you’re aware of it, let me know.

Now let’s move to the things that one can do

that have been shown to have, let’s just be honest,

pretty enormous effects on growth hormone release

in waking and these are things that are very actionable.

One of the things that can have a dramatic effect

on levels of growth hormone release in waking

as well as in sleep the following night is exercise.

But the key is the type of exercise and the duration.

Now there’s a logic to this.

There are hundreds if not thousands of studies

measuring growth hormone both during

or sometimes after exercise or the following night.

And the conclusion that one takes away from all of these

is that exercise has to be of particular duration

and intensity in order to get growth hormone release.

So first I’m just going to tell you what I found

to be the maximum amount of growth hormone release

as it relates to a particular form of exercise.

The particular form of exercise is either weight training

or it can be endurance training,

but the endurance training and the weight training

actually have to be limited to about 60 minutes,

not much longer.

Now this is important because it’s been shown

over and over again that if one exercises too long

with weights or endurance exercise,

that cortisol levels go high enough

that it starts to inhibit the testosterone

and even the estrogen pathways.

This is why I believe people who overexercise

or exercise a lot can lose their menstrual cycles,

they stop menstruating.

It’s why you get suppressions in testosterone

if people train too long and too hard.

The cutoff has always been, you know,

60 to 75 minutes of the hard work part.

It’s going to vary a lot from person to person.

But in terms of growth hormone,

the conditions that seem to lead

to the greatest growth hormone release

are one, get warm.

This is interesting.

We’re going to talk about temperature.

So a proper warmup seems to accelerate

the release of growth hormone

once the hard work phase starts.

So 10 minutes of warmup or so

was the number that I extracted from all these studies.

There’s a beautiful review on this, by the way.

Growth hormone responses of varying, excuse me,

growth hormone, arginine and exercise.

We’ll talk about arginine in a few minutes.

That’s by Canaley, K-A-N-A-L-E-Y.

It was published in Current Opinion

in Clinical Nutrition and Metabolic Clare.

The Current Opinion journals

are generally of pretty high quality

in terms of the reviews,

just because they tend to be pretty recent.

And then the references therein are also quite good.

So what does this mean?

This means warmup.

And when you say warmup,

it doesn’t mean just warm up the limbs and tissues

that you’re going to use so you don’t get injured,

actually warm the body.

So there was actually some discussion

about whether or not in cold winter months,

people should wear like a stocking cap,

bringing the conditions, making the room warm.

So getting the body warm as a warmup seems to be important

because temperature of the body

seems to be an important condition

or prerequisite for certain patterns of exercise

to maximize growth hormone release.

So this is really interesting to me.

I have an obsession

with how body temperature, light exercise and food interact.

We’re going right there with the fact that if you get warm,

you bring up the body temperature degree or two

or maybe three and then start exercise.

It does appear that high intensity exercise,

but again, as discussed in a previous episode,

not exercise that brings muscles to failure,

but close to it.

So if it’s weight bearing exercise,

it would be getting close to that final repetitions

where you can’t complete them,

but not pushing through those

or even going to failure, but getting close

leads to anywhere from 300 to 500% increases

in resting growth hormone levels

and 300 to 500% increases in growth hormone

the following night when you go to sleep,

which is incredible.

Now, I want to dissect this properly, okay?

So one of the other conditions that seemed to be important

again was to have relatively low blood glucose.

So it’s looking a lot like the conditions you need for sleep

in order to get maximum growth hormone release in sleep.

So not having blood glucose too high or too low,

that’s a discussion unto itself.

You want to have sufficient energy to do the exercise,

but getting warm,

not having blood glucose too high or too low,

so probably not eating too close to exercise

or not ingesting a lot of sugars during the exercise.

That was supported by the fact

that ingestion of a sports drink

that contains caloric sugar

immediately flatlined the growth hormone levels.

So really interesting relationship

between insulin, glucose, and growth hormone.

So then doing the training

for anywhere from 60 to 75 minutes

to maximize growth hormone release.

And then the other interesting thing

was that even after the exercise,

taking body temperature back down to normal levels

relatively quickly seemed to be associated

with these big spikes in growth hormone.

Otherwise, what would happen

is you get these big spikes in growth hormone,

but if the exercise went too long

or if body temperature remained too high for too long,

then you didn’t get the second increase

in growth hormone the following night, okay?

So I hope I made that abundantly clear.

Warm up well, get body temperature up,

exercise 60 to 75 minutes.

Don’t go to absolute failure

if your interest is in growth hormone release,

both during the exercise and later that night.

And if you can bring body temperature back down

to normal levels by cooling off,

maybe cool shower or maybe ice pack or something,

or maybe just turning off the heat in the room

or going outside, whatever it is,

then you increase the probability

that you’re going to increase growth hormone

the following night as well.

And again, these are big increases, 300 to 500%.

It’s almost like you’re getting

a second sleep during the day.

But if the exercise is too hard,

if body temperature stays too high for too long,

you disrupt the whole process

and you don’t get the effect of increased growth hormone.

Growth hormone is really powerful,

but it doesn’t work alone.

In fact, a lot of the effects of growth hormone

are mediated by its effects on the liver.

So growth hormone is released, goes to the liver,

and then the liver releases something called IGF-1,

insulin growth factor one.

Insulin growth factor one was popular

in the neuroscience community as an area of focus

because of its ability to trigger improvements

in memory and learning after exercise.

And indeed, exercise triggers both the release

of growth hormone and IGF-1.

IGF-1 seems responsible for a lot of the effects

of improved memory.

Some people report that that is due

to increased number of neurons or neurogenesis,

birth of new neurons.

It’s pretty clear that in humans,

that’s not what’s happening.

Yes, in animals, not in humans.

IGF-1 nonetheless has positive effects

on memory and cognition.

And a great way to trigger IGF-1 release

and growth hormone release is through exercise.

Now, the interesting thing,

and the reason I’m bringing up IGF-1 here

is that certain patterns of exercise,

actually duration of exercise,

have different effects on IGF-1 and growth hormone,

depending on whether or not the exercise

is done by men or women.

There’s what we call a sex-dependent effect.

And the sex-dependent effect is as follows.

In this particular study and several others,

what they did is they had people exercise.

They measured growth hormone and IGF-1 levels

from the blood before, during, and after exercise.

And they could see when the greatest increases occurred.

This was standard sorts of resistance exercise.

So some squats, there was a sprint-like activity.

It doesn’t really matter what the specific exercises were.

None of them were to failure.

These were in kind of the 10 repetition or less range,

six sets, so kind of standard weight training stuff

that anyone might do.

But what was interesting is that women were able to access

the biggest peak in growth hormone and IGF-1

early in the exercise, so in the first 30 minutes.

So what this means is even if you just have 30 minutes,

at least for women, there’s going to be a big increase

in growth hormone and IGF-1 in the first 30 minutes.

For men, the biggest increase occurred later

in the exercise, which was 60 minutes or so total.

And so the sex-dependent effects are interesting.

They point to the fact that things like cortisol,

testosterone, and estrogen, which of course vary

in different levels in men and women,

are going to impact the release of things like IGF-1

and growth hormone.

And yes, they did control for all sorts of things

like diet and they controlled for weight

and prior experience.

It’s actually a quite nice study.

If you’d like to check it out,

it’s by Pierce et al.,

Growth Hormone Insulin Glow Factor 1 Molecular Weight

Isoform Response to Resistance Exercise

are sex-dependent in frontiers in endocrinology,

fine journal in 2020, so it’s quite recent.

So what does this mean?

This means if you’re exercising

and you want growth hormone release, warm up,

do the type of exercise we’ve been discussing.

Women in the first 30 minutes is when you’re going to get

the maximum benefit in terms of growth hormone and IGF-1.

Men, you have to keep going for the entire 60 minutes,

so don’t tap out early if you’re interested

in getting the growth hormone and IGF-1 release.

And the same conditions apply about then cooling down

and not making the exercise last so long

that you don’t get the increasing growth hormone

the following night.

My experience thus far in doing this podcast

is that people fall into one of two categories.

There are the just tell me what to take people,

the people that are really eager to try supplements

and maybe even prescription compounds.

And then there are people who are a little bit more shy

about supplementation.

They are more focused on what they can do with diet

and behaviors and things of that sort.

I don’t have a bias either way.

I try and offer tools that are supported

by the scientific literature.

And I always point to safety margins.

There are supplements that can increase growth hormone

to a considerable degree.

And no, these aren’t growth hormone itself,

although that of course will increase growth hormone

to a considerable degree.

We will talk about prescription drugs at the end,

not just growth hormone,

but some other things that are quite prominently

in use right now,

in particular in the entertainment industry.

It’s pretty interesting compounds.

But first let’s talk about supplements.

So this has been known about for some time,

but arginine, the amino acid arginine,

as well as the amino acid ornithine

can increase growth hormone levels substantially.

Now, arginine has a number of effects.

You can get it from food.

You can get it from supplements.

Some people take it in pill form or capsule form.

Some people will actually take it by IV intravenously.

The levels and the amounts of arginine required

to get big growth hormone release increases

is pretty substantial.

So some people will take arginine before bedtime.

Some people will take it before exercise.

Prerequisite again is low blood glucose.

Blood glucose is high.

It’s going to quash the effect.

The amounts of arginine that people take

are anywhere from three grams to 10 grams

or sometimes even more.

Although this is definitely a case of more is not better.

There is a threshold at which growth hormone release

is actually blunted by taking more than nine grams

of arginine.

Now, nine grams of arginine orally is a lot of pills.

It’s at minimum nine pills

and it can cause some GI disturbance, right?

People can feel nauseous.

Some people will throw it up.

Some people get some constipation or diarrhea, et cetera,

or just stomach aches.

I’m certainly not suggesting people do this.

They’re not that they take arginine,

but that’s the reason why most of the studies

that looked at the role of arginine

on growth hormone levels did it by IV, intravenous infusion.

So what’s interesting, however,

is that whether or not it’s by mouth or by vein,

taking arginine can dramatically increase

growth hormone release.

And the levels or the amount of increase

was anywhere from 100 on the low end,

but anywhere from basically from 400 to 600%

above baselines.

These are huge increases in growth hormone.

Now, I’ve never tried arginine.

Arginine is out there for a number of different purposes.

One of them is to increase growth hormone.

As some of the supplements out there

to increase growth hormone include arginine and ornithine.

Arginine does have the effect of dilating arterioles

and it basically increases blood supply.

The arginine pathway is involved in vasodilation.

It’s actually the pathway that’s downstream

of a lot of drugs that are used

to treat things like erectile dysfunction.

And anytime people have problems

with peripheral blood flow of any kind,

they focus on compounds that will either disrupt the enzymes

or will adjust the levels of amino acids

to get more vasodilation.

So taking arginine for the purpose

of increasing growth hormone will also have the effect

of dilating blood vessels.

And for people with heart conditions

that actually can be a serious issue.

Now, here is something really important

and interesting to note,

which is that increasing arginine levels

with the specific goal of increasing growth hormone release

can actually short circuit the effects

of exercise on growth hormone.

Several studies I looked at,

looked at the interaction of taking arginine

and the exercise or just the arginine

or just the exercise alone.

And so you don’t, unfortunately,

if growth hormone increases your goal,

you don’t unfortunately get to increase growth hormone 800%

by taking arginine and exercising.

It always seems to be clamped

at about 300 to 500% increases, still large increases.

So I make that point for several reasons.

First of all, be aware that arginine

has these other effects on vasodilation.

Take those seriously if you have a heart condition

or take them seriously in any case.

Second of all, you can supplement with arginine,

not exercise and get these big increases in growth hormone

by taking them before sleep.

But if you’re taking the arginine before exercise,

you are going to short circuit

or clamp the effects of exercise on growth hormone, okay?

So it’s something that one could use,

but it doesn’t have a synergistic effect with exercise.

The two more or less cancel each other out, not to zero,

but you end up with the same effect you would

had you done one or the other.

So hopefully that’s clear.

The other thing is if one’s goal

is really to increase arginine in the blood

for whatever reason,

arginine may not actually be the best way to do that

because of the way it’s metabolized in the gut.

It doesn’t have access or get access to the tissues

that you’re most interested in

in terms of increasing growth hormone

or vasodilation for that matter.

And in that case,

there’s something else called L-citrulline

which has powerful effects on vasodilation,

powerful effects potentially on growth hormone levels

via the arginine pathway.

But basically L-citrulline acts as sort of a donor

or it’s kind of a biological prerequisite for arginine

and can lead to even bigger arginine increases

than you would get if you took arginine itself.

And so L-citrulline is out there

but keep in mind that anything that dilates the blood vessels

will lower blood pressure.

So L-citrulline, yes, will lead to increased blood flow

for whatever purpose you want to use it for,

whether or not that’s pumps in the gym or whatever.

It also can lead to big increases

in arginine and growth hormone,

but it will lower blood pressure.

So be aware of that

but and understand that the biology

isn’t so straightforward.

L-citrulline may actually be the better way

to get arginine increases than arginine itself.

And ornithine can also increase growth hormone,

although that’s also through an indirect pathway.

And nowadays there isn’t a lot of focus on ornithine

as a way to increase growth hormone.

That was kind of all the rage in the 90s,

not so much anymore.

Nowadays, the people who are really in the know

for this stuff tend to focus on L-citrulline.

And if you’re interested in L-citrulline or arginine,

I highly recommend you go to our old friend,

good friends, examine.com

because there you can put it into the list.

You can just put search and it’s totally free.

And it will tell you

that blood pressure will be slightly decreased.

Power output in the gym will increase.

There’s very strong effects on blood glucose.

Fatigue is reduced notably.

Big increases in nitric oxide.

That’s also related to the increase in vasodilation.

Plasma arginine, very high effect, excuse me,

notable effects, very high support for studies

which allow people more training volume,

aerobic exercise, arterial stiffness is brought down.

There’s a huge list of things.

Increase in growth hormone.

So two studies showing this was done double blind.

Great, you always want to see double blind,

placebo controlled.

This was only done in males, not in females.

Unfortunately, just have data from males,

but increases in growth hormone.

It’s a small, but a real significant effect.

And again, from quality studies.

So there’s a huge number of effects there.

And some of the other kind of more interesting ones

about L-citrulline that you might not have thought about

are things like muscle oxygenation.

As we scroll down, decreases in C-reactive protein.

So a lot of the same things that you might expect,

excuse me, from the same sorts of compounds we saw before.

The takeaway here is if you want to increase growth hormone,

think about the arginine pathway,

but arginine itself might not be the best direct route

to get there.

L-citrulline might be a better option,

but please do consider and take very seriously

the effects on blood pressure.

So we’ve been talking about big effects

from supplementation or exercise on growth hormone,

this extremely powerful hormone.

And one thing to note is that the profile of growth hormone

as we age changes.

I mentioned that earlier,

but it’s important to understand how it changes.

One thing that’s particularly interesting to me

as somebody who’s in his 40s

is that it’s actually between ages 30 and 40

that the amount of growth hormone that you release

each night is reduced by two to threefold.

That’s really incredible.

You know, we hear so much about testosterone levels

going down as we age or estrogen levels going down.

But if you recall from the testosterone and estrogen episode

talked about the fact that if you really look at the data,

just for instance, on testosterone,

there are men in their 90s and they are not rare,

it turns out, that are making as much testosterone

and DHT, dihydrotestosterone, as they were in their 20s.

Okay, so we hear so much nowadays

about how testosterone levels are dropping,

sperm levels are dropping, et cetera.

And I don’t dispute that.

I talked about that in that episode.

But it’s clear that testosterone levels

vary tremendously from person to person.

And just getting older does not necessarily mean

that testosterone levels are dropping.

Growth hormone levels, it seems,

are dropping when people are in their 30s and 40s

and they’re dropping substantially.

And that seems to be the case across the board.

You’re just not going to find people in their 40s, 50s,

and 60s that are making as much growth hormone

as they were in their teens and 20s.

And as somebody who, I feel really good,

but as somebody who definitely noticed

that as I got into my 40s,

that even if I slept the same amount,

I wasn’t feeling quite as, I would say,

able to recover from exercise or wound healing,

even with the same amount of sleep.

And I was trying to optimize a great number of things.

This business of growth hormone

became a particular interest to me.

And since the ways to manipulate growth hormone

in men and in women are so straightforward,

and since everybody goes through this age-related decline

very dramatically, it seems to me that the things

that we’re supposed to be doing anyway, like exercising,

like trying not to eat too close to bedtime,

trying to optimize sleep,

all of these are wonderful tools

that we should be pursuing and perhaps using.

And they can actually offset

the two to three-fold decrease, right?

If we’re talking about a two to three-fold decrease

for people that are in their 30s and 40s,

and then we’re talking about increases from exercise

or from maybe from supplementation,

but certainly from exercise of 300 to 500%,

well, then all of a sudden we’re in a position

to actually offset the age-related decline

in growth hormone completely just through behaviors.

And I think that’s quite interesting and quite powerful.

Now I’d like to discuss a way

that anyone can increase their levels

of growth hormone dramatically.

And when I say dramatically, I mean dramatically.

I’ll get to the numbers in a couple minutes,

but we have to remember how growth hormone

is released in the first place.

Remember, it all starts in the brain, in the hypothalamus.

The hypothalamus is a brain area

that controls things like sexual behavior,

temperature regulation, circadian behavior,

meaning when you want to be awake

and when you want to be asleep, aggression, all of that.

There are other brain areas involved too,

but it has a rich collection of different neurons

involved in all these very basic functions.

Now, as we talked about the releasing hormones,

the growth hormone releasing hormone

comes from neurons in the hypothalamus.

Those then communicate with the pituitary

and the pituitary releases growth hormone.

And then the growth hormone acts

on all these different tissues,

muscle, liver, cartilage, et cetera, body fat.

Makes them use energy.

That’s why you lose body fat

when growth hormone levels are high.

It makes you grow muscle, strengthens bones, et cetera.

Now, one of the things that has a profound effect

on growth hormone levels,

growth hormone release is temperature.

Now, the data on this are very strong

and the data come from both animal studies

and human studies.

So there are a number of studies that have explored

how making animals cold or hot can increase growth hormone.

And if you’re guessing which direction this is going to go,

you can probably imagine that making animals

or people warmer is the way to go

if you want to increase growth hormone.

Now, anytime you’re going to increase temperature

of yourself or anyone else or an animal, it is risky.

I want to be really clear about this.

Not everyone should engage in the behaviors

I’m about to describe.

But, and I should just say the reason it’s risky

is it doesn’t take much of a temperature increase

in the brain to cook the brain, to cook neurons.

And after that point, neurons can’t come back

and people can die from hyperthermia.

We have a much greater range in terms of cold.

You can also die of hypothermia.

You can freeze to death,

but you have a much greater range of getting cold

than you do warming up the brain.

However, there are really strong data

pointing to the fact that sauna,

aka deliberate hyperthermia, not too high, however,

that sauna can increase the release of growth hormone

and other hormones.

And what’s so dramatic about this literature

is the size of the effects that are reported.

So first of all, let’s talk about

these temperature increases.

And yes, I will refer to things that people can do

even if you don’t own a sauna,

because I realize not everybody has a sauna

in their backyard or has access to a sauna.

So first of all, recall our study about exercise,

where warming up a few degrees before the exercise

led to bigger and quicker increases in growth hormone

during the exercise bout itself.

So that already point in the direction

that temperature was important.

Now, the degrees, no pun intended,

that we’re talking about increasing body temperature

is by entering saunas that are somewhere

between 176 degrees Fahrenheit,

so that’s 80 degrees Celsius,

and all the way up to like 210, 215 degrees Fahrenheit.

I personally know people that go even higher than that,

but they’ve trained themselves to deal

with very high heats.

And again, high heat is dangerous.

You must clear this with your doctor.

Now, what happens in high heat?

A couple of things happen in high heat.

First of all, you start getting bigger stroke volume

of the heart, kind of like an exercise.

Once you get well-trained in endurance activity,

your stroke volume, the amount of blood

that your heart can pump each time gets larger.

You dilate the blood vessels, right?

There are a lot of things that happen also.

You’re sweating, your body’s trying to unload heat.

Dilation of blood vessels, arginine increases in heat.

We’re starting to see and hear a common theme,

but it appears that getting into,

I’m not saying getting the body up to 212 degrees Fahrenheit.

I want to be very clear.

I’m not talking about getting the body

up to 100 degrees Celsius.

That would be terrible.

You would die.

But entering environments where it’s very hot

for short periods of time,

anywhere from 20 minutes to 30 minutes,

where the temperature is 80 degrees Celsius

to 100 degrees Celsius, or 175 degrees Fahrenheit,

more or less, to about 210 degrees Fahrenheit, more or less,

has been shown to increase growth hormone release 16-fold.

That’s right, 16-fold.

That’s 1,600%.

Now, there are also effects on other hormones,

prolactin, cortisol, et cetera.

So the pattern that was described in this study,

and there’ve been many studies now,

endocrine effects of repeated sauna were done in 17 humans.

This was from doing this repeatedly.

So it wasn’t the first time they did this.

They actually had to do this three days in a row.

And the pattern was to get into the sauna for 20 minutes,

followed by a 30-minute cooling period.

Remember, you don’t want to spend long periods of time

at high heat.

You can cook your brain and other tissues.

Be very careful as you approach this if you decide to.

But 30 minutes, excuse me, 20-minute sauna,

followed by 30 minutes of cooling,

followed by 20-minute sauna again,

led to a five-fold increase in growth hormone.

And then by doing that day after day after day,

on the third day, you would see these huge increases

of like 16-fold, up to 16-fold.

And there are now many studies like this.

This was described a few years ago.

But since then, there have been a number of other studies

that have pointed in the direction of

deliberate hyperthermia, but not too hot,

that you kill yourself in order to increase growth hormone.

And I know I keep highlighting the dangers there,

but again, anytime you’re going to mess with heat,

you have to be cautious.

You have to be careful.

So standard sauna can be useful.

If you don’t have access to a sauna,

one way that people do this,

we have to look to our friends, the wrestlers, right?

They wear plastics, which are basically body suits

that are fairly inexpensive that you can buy

on any online purchase platform, I should say.

Some people in the old days,

before they had these plastics things so readily available,

I actually knew people that wrapped themselves

in garbage bags and then throw on sweats and a hoodie

and then go out for a jog.

Again, you have to be really careful,

especially on a hot day, overheating can equate to death.

But that’s another way to heat up.

You don’t actually need a sauna.

I’ve known people who will do this in hotel rooms

while they’re traveling.

They’ll turn on the heat, make a hot bath.

They won’t actually get in the bath,

but they’ll fill the room with steam and heat

and they’ll put on a hoodie and some sweatshirt, sweatpants,

and they’ll sit there with wool socks on

and they’ll get warm for 20 minutes.

Then they’ll take a cool shower and then they’ll do it again.

I guess when the hotel’s paying the water bill,

you don’t worry about it too much.

Some people, of course, own saunas.

There are a lot of ways to do that.

I have friends who were in the military

who made saunas out of cars while they were overseas,

all sorts of things.

You do have to be careful.

I know I’ve said it many, many times.

I just don’t want anyone to hurt themselves.

But these increases in growth hormone are tremendous.

And what they probably stem from

are increased activity of neurons within the hypothalamus

that stimulate growth hormone release from the pituitary.

And that’s probably because the growth hormone

releasing hormone neurons in the hypothalamus

sit very closely and may even be intermixed

with some of the neurons in the hypothalamus

that regulate heat and body temperature.

Remember, metabolism is in part a heat.

It’s like a furnace of how much energy

you’re consuming and using for building

or for energy usage purposes.

So sauna can be very, very interesting.

And again, it’s 20 minutes, 30 minute cooling,

20 minutes again, proceed with extreme caution.

But nonetheless, these are pretty extreme effects

in terms of their abilities

to increase growth hormone levels.

Along the lines of temperature and hormones,

I just want to mention a very recent study just came out,

March, April, 2021.

Endocrine effects of repeated hot thermal stress

and cold water immersion in young adult men.

Unfortunately, it was just in men.

They didn’t look at women, but nonetheless,

I think the data are relevant to everybody

as a general theme.

This is Podstowski et al.

I will put a link to the study in the caption.

And they looked at testosterone, prolactin, cortisol,

et cetera, and what they found was that the sauna

does indeed lead to a significant decrease in cortisol,

a stress hormone, a hormone that you want to be released

early in the day when you wake up.

But sauna definitely led to a significant decrease

in cortisol, but did not change testosterone,

DHEA, or prolactin levels.

So that’s interesting.

And it turns out that the cold did affect

some of these hormones, but the results there

were a little bit more mixed.

So the takeaway here is that heat seems to have

positive effects on growth hormone, big effects.

It seems to have positive effects

on reducing cortisol levels.

And it does not seem to have effects on things

like testosterone, DHEA, or prolactin directly.

You can imagine that a shift in any hormone

is going to alter the levels of other hormones

down the line, sort of indirect effects.

But in terms of direct effects, just during

or immediately after the sauna bath, there were no effects.

So we’ve talked about diet, supplementation,

behavioral tools, and of course, we talked about

the underlying biology and logic.

And hopefully you heard the safety precautions

for all of those.

Now I’d like to just briefly talk about

the prescription side of all this.

There are, as we know, many people taking growth hormone

because it’s been prescribed to them by a doctor.

And presumably there are people taking growth hormone

even though it has not been prescribed by a doctor,

which is none of my business.

But the point here is that most all of the hormones

that we make have been synthesized.

So there are versions of them in little bottles

or little ampules that people can inject.

Here are a couple of important things to consider.

If you’re going to go that route.

First of all, talk to a physician, right?

They actually are only legally available

through a physician.

Second of all, anytime you’re injecting something,

you’re going to shut down your own production.

That’s the way that the hormone system works.

If you take thyroid hormone, you won’t make thyroid hormone,

at least in the long run.

If you take testosterone, you will shut down

your own production of testosterone.

If you take estrogen, the system’s a little more resilient,

but eventually you will shut down

your production of estrogen.

And the same is true for growth hormone.

So a decision to go that route of taking something

is often not always a decision to do it forever.

However, if you’re willing to sustain a period

of being without a given hormone,

some people can do things and then stop taking them

and then wait out the period in which they’re not making

testosterone, estrogen, or growth hormone,

and then it will come back.

Sometimes, and sometimes it won’t.

There’s a kind of new area that’s developing now

that I think deserves our attention,

not because I’m encouraging it, but because it is happening.

And in keeping with the science and in keeping with trying

to keep things modern, it’s worth us discussing.

And those are peptides.

So these days you hear a lot about peptides.

I’d like to clarify a little bit about what peptides are.

Peptides is a really huge category of biological compounds.

Peptides are just strings of amino acids, right?

So we’ve talked about l-tyrosine, arginine, ornithine.

Those are amino acids.

Those are individual amino acids.

And those are put together into little small peptides

or they’re what are called polypeptides,

which are just longer peptides.

Turns out that for any substance like growth hormone

or growth hormone releasing hormone,

it’s made up of different amino acids in different sequences

just like your genes are made up of A’s and G’s

and C’s and T’s, nucleotides in different sequences.

It’s like a recipe.

Peptides tend to be short sequences of amino acids

that resemble a hormone enough

or resemble some other peptide enough that it can lead

to the similar or same effects when you inject them.

So for example, we make growth hormone releasing hormone

from our brain, which stimulates growth hormone

from the pituitary.

You’re probably getting tired of me saying that by now.

But people now will take things like sermorelin,

S-E-R-M-O-R-E-L-I-N, sermorelin,

which is not the entire peptide sequence

of growth hormone releasing hormone,

but it’s a subset of those.

And when people inject it before they go to sleep at night,

it’s typically how it’s done on an empty stomach,

then that stimulates the release of growth hormone

from the pituitary.

So this is not taking growth hormone.

This is taking the stimulating hormone

or what’s often called a secretagogue or a mimic.

All right, it causes a secretion

of the hormone that one wants.

People will do this for thyroid hormone too.

Some people are doing this by prescription

with a real medical need.

Other people are doing it for just longevity reasons,

which kind of falls into that gray zone

of they wouldn’t die without it,

but they want to enhance their life.

And so they’re doing that

because they believe it’s the right thing for them.

Prescription, sermorelin is prescription.

Do they work?

Yes.

Do they shut down your natural production

of growth hormone releasing hormone?

Well, the answer is yes,

but some of these peptides actually have the effect

of changing gene expression.

Remember way back to the beginning

when I was talking about hormones,

they can actually change gene expression

and they can actually set pathways in motion

for continued production of a hormone,

even if you stop taking the compound.

Now that can be good or that can be bad

because as you recall,

big increases in growth hormone that are short-lived

like sauna, or I should say exercise,

or arginine, or sauna,

it seems like has these huge effects,

or early nights, first phase of sleep early in the night,

these sorts of things.

Those are transient,

but when one is injecting over and over a constant level,

you can put into action gene expression programs

that can be long-lived.

And let’s say you have a particular tumor in the body,

tumors will grow when they see growth hormone,

even if that tumor is unhealthy for you, right?

You’ve got growth of tissues all over the body.

So again, I’m not saying whether or not

people should do these things or not doing them.

One thing I do know is that they are in very prominent use

in the movie industry,

people who want to peel off body fat quickly,

they do increase recovery time,

they increase healing rates.

People are also injecting things like gastric peptides.

They’re actually stomach peptides

that we talked about in the previous episode.

Things related to the ghrelin pathway

and other things from the liver

that can improve the rate of tissue and wound healing.

You can bet that in the upcoming Olympics,

a lot of people are using peptides and compounds

and I’m not pointing fingers at anyone in particular.

It’s just, this is separate from hormone augmentation

of like injecting GH or injecting testosterone.

People are now working further up the pathways.

Other names of some of the peptides

are things like ipermoralin, tesamoralin.

Some of these have clinical uses.

Others have just been made as compounds for people

in the kind of longevity field

or the self-augmentation field, if you will.

So again, not promoting their use,

but they’re definitely out there.

And so now if you hear about them

or someone’s talking to you about them,

now hopefully you have a better understanding

about their underlying biology

and you can think rationally about whether or not

they are the right decision for you.

Okay, once again, covered an enormous amount of material.

Hopefully now you understand thyroid hormone

and what it does and a little bit about its mechanism

or maybe a lot and growth hormone and what it does

and how both of them take care of our metabolism.

They dictate how many nutrients we can eat and make use of.

They can pull from body fat stores,

repair muscle, repair cartilage.

They really are incredible compounds

and they’re actionable.

There are things that we can do

like getting that early phase of sleep,

perhaps supplementing with arginine, maybe not.

Hopefully getting adequate exercise, warming up properly,

not making the exercise too long or too intense will help.

Maybe sauna or things like it,

deliberate safe hyperthermia, the emphasis on safe,

might be things that are of use.

Regardless, even if you’re not interested in the thyroid

or the growth hormone pathways,

this brings to a close our month on hormones.

And so now hopefully you understand

not just thyroid and growth hormone,

but the logic that underlies thyroid hormone,

growth hormone, estrogen, testosterone,

why we eat, why we stop eating,

cholecystokinin, ghrelin.

If these names don’t mean anything to you,

then perhaps go back and listen to those episodes.

But regardless, I hope that you come away from this

with a deeper understanding about these hormones,

which are so powerful in controlling

the way our brain functions

and the interplay between the brain and hormones,

because it is really a bi-directional conversation.

The brain is telling the body what hormones to make,

the hormones are influencing all the tissues of the body,

but also telling the brain whether or not to eat more

or grow more or think more, et cetera.

So I really appreciate your time and attention.

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