Huberman Lab
Essentials: How to Control Your Metabolism by Thyroid & Growth Hormone
Thu, 06 Mar 2025
In this Huberman Lab Essentials episode, I explain how two key hormones control metabolism and discuss tools to enhance their levels to improve metabolic health. I discuss the pathways through which the brain and body interact to produce thyroid hormone and growth hormone, and how these hormones influence essential processes like tissue growth and repair, body composition, and energy production. I explain how thyroid hormone levels are influenced by key nutrients, such as iodine, selenium, and L-tyrosine. I also explain how practices such as exercise, sleep, meditation and sauna can offset age-related declines in growth hormone, to optimize overall hormone health and metabolism. Huberman Lab Essentials are short episodes (approximately 30 minutes) focused on essential science and protocol takeaways from past Huberman Lab episodes. Essentials will be released every Thursday, and our full-length episodes will still be released every Monday. Read the full episode show notes at hubermanlab.com. Thank you to our sponsors AG1: https://drinkag1.com/huberman Eight Sleep: https://eightsleep.com/huberman David: https://davidprotein.com/huberman Timestamps 00:00:00 Huberman Lab Essentials; Hormones & Metabolism 00:01:41 Hypothalamus, Pituitary, Thyroid 00:03:22 Thyroid Hormone Functions, Tools: Iodine, Selenium, L-Tyrosine 00:07:55 Sponsor: Eight Sleep 00:09:27 Thyroid Hormone, Glucose & Metabolism; Thyroid Hormone Disorders 00:11:45 Growth Hormone Functions, Prescription Growth Hormone 00:14:41 Growth Hormone Release, Tools: Sleep & Bedtime Fasting 00:16:07 Growth Hormone Release, Tool: Meditation 00:18:21 Sponsor: AG1 00:19:24 Growth Hormone Release, Tools: Exercise, Warm-Up, Glucose, Cool Down 00:22:04 Growth Hormone Supplements, Arginine 00:24:07 Offsetting Age-Related Growth Hormone Decline 00:25:05 Temperature & Growth Hormone, Tool: Sauna Protocol 00:29:23 Sponsor: David Protein 00:30:38 Peptides, Sermorelin, Secretagogues, Risk 00:33:26 Recap & Key Takeaways Disclaimer & Disclosures
Chapter 1: How do thyroid and growth hormones influence metabolism?
Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health, and performance. 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. 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. 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 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 etc 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. There are neurons in your brain in an area called the hypothalamus.
which 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 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.
The thyroid is a little butterfly-shaped gland that's right around the Adam's apple, and it's got four little bumps behind it called the parathyroid gland, and it releases thyroid. 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.
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Chapter 2: What nutrients are essential for thyroid hormone production?
The thyroid needs iodine in order to produce thyroid hormone. 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. 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 100 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. 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 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 you know pork beef turkey chicken cottage cheese eggs what you want to understand is that 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 i also want to mention that for children their daily requirements of selenium are much lower as low as you know 30 or 40 micrograms for kids 14 years or younger 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
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. I'd like to take a quick break and thank our sponsor, Eight Sleep.
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Chapter 3: How does sleep affect growth hormone release?
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 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. 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 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. I'm 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, 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.
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. As always, I want to emphasize, talk to a doctor before you do anything, including remove any treatments.
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Chapter 4: Can meditation enhance growth hormone activity?
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 Goleman 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.
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 states 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 brain waves.
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. I'd like to take a quick break and acknowledge our sponsor, AG1. AG1 is a vitamin mineral probiotic drink that also includes prebiotics and adaptogens.
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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. There are hundreds, if not thousands of studies measuring growth hormone, both during... or sometimes after exercise or the following night.
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