Episode 17: How To Control Your Metabolism By Thyroid & Growth Hormones | Huberman Lab

Key Takeaways

  • Metabolic functions include repair of injury and brain tissue, clearance of damaged neurons, and energy for cells – not just BMI and weight-related concerns
  • Thyroid and growth hormones have similar pathways and are both critical to metabolism and repair and growth of tissues
  • Iodine, L-tyrosine, and selenium (found in Brazil nuts) are all important for proper thyroid hormone production and function
  • Some “clean” diets can interfere with thyroid functions by disrupting iodine pathway – plant-rich hard diets make it challenging to get enough L-tyrosine; with a carnivore diet it is hard to get enough iodine
  • Growth hormone release peaks in puberty and decreases 2-3 fold between 30s-40s
  • Lifestyle activities to increase growth hormone: (1) increase slow wave/deep sleep; (2) exercise 60-75 minutes – but not working to failure which increases cortisol; (3) sauna at 176-210F for 20-30 minutes – increase growth hormone 16 fold; (4) supplement with arginine, ornithine, or L-citrulline
  • Arginine supplementation caution: potent vasodilator and blunts growth hormone benefits of exercise
  • Most hormones we make have been synthesized and are available by prescription or on the market but use with caution – any time you intake an exogenous hormone, your body stops producing on its own


Dr. Andrew Huberman, Ph.D. is a Professor of Neurobiology and Ophthalmology at Stanford University School of Medicine. His lab focuses on neural regeneration, neuroplasticity, and brain states such as stress, focus, fear, and optimal performance.

In this episode of Huberman Lab, Dr. Huberman takes a deep dive into metabolism, specifically how thyroid and growth hormones control metabolism, how to leverage hormones to positively impact hormones, factors for changing levels of thyroid and growth hormones, and much more.

Host: Andrew Huberman (@hubermanlab)

Overview of Metabolism

  • Metabolism isn’t just about losing weight
  • Metabolism is the consumption of energy and use of energy in the cells of the body for growth, repair, and maintenance of tissues
  • Functions of metabolism include repair of injury, repair of brain tissue, clearance of damaged neurons rate to fuel consumption – not just BMI and weight-related issues
  • Most of resting metabolic needs are for the brain – 75% of metabolic needs come from the brain
  • Muscle burns more energy than fat
  • Metabolism can be increased by increasing muscle and/or reducing fat

Physiology Of Hormone Release & Thyroid

  • The brain releases hormones; the pituitary stimulates hormones
  • Example: thyroid releasing hormone in the brain tells the pituitary to release thyroid stimulating hormone
  • The thyroid hormone controls many features of the face and eyes but its main role is to promote metabolism and convert energy
  • Thyroid hormone acts on muscle, liver, cartilage, and bone
  • Thyroid needs sufficient levels of iodine to produce thyroid hormones
  • Thyroid increases glucose uptake and bone mineral density with age
  • Some markers of hyperthyroidism: bulging eyes, trouble maintaining weight, shakiness  
  • Some markers of hypothyroidism: thinning of hair, difficulty losing weight
  • Levels of thyroid hormones can fluctuate throughout menstrual cycle
  • Ketogenic diet may negatively impact thyroid hormone once carbs are reintroduced because carbohydrates stimulate production of T3 and T4

Iodine And Selenium For Thyroid Health

  • Iodine (found in table salt) works with L-tyrosine to produce T3 and T4 thyroid hormones
  • Goiter: thyroid disfunction from lack of iodine presents as bulging thyroid in the throat
  • The thyroid doesn’t need much iodine, you can get enough even by breathing coastal air regularly
  • Some “clean” diets can interfere with thyroid functions by disrupting the iodine pathway – plant-rich hard diets make it challenging to get enough L-tyrosine; in a carnivore diet it is hard to get enough iodine
  • L-tyrosine and iodine-tyrosine compound can be taken as a supplement
  • Iodine can also have an anti-inflammatory effect
  • Selenium increases thyroid hormone production by allowing L-tyrosine and iodine to interact
  • Brazil nuts are the largest sources of selenium – also present in tuna, shellfish, pork in much smaller doses
  • Selenium is important for offsetting pre-eclampsia risk (high blood pressure in pregnancy)
  • Some evidence that selenium can also reduce prostate cancer risk

Growth Hormone

  • Mechanism and functions of thyroid hormone and growth hormone are similar
  • Growth hormones come from the brain and are released to the pituitary which stimulates bone, muscle, fat to increase metabolism
  • Growth hormone is also involved in the metabolism and repair and growth of tissue
  • During puberty and development pituitary releases a surge of growth hormone but tapers after that
  • Profile of growth hormone changes over time: between the 30s-40s, growth hormone decreases two to three-fold
  • Problem with injecting growth hormone unnecessarily: causes growth of all tissues, not just muscle – so it can lead to the growth of heart, liver, spleen, etc.
  • Many effects of growth hormone are mediated by an effect on the liver which releases insulin growth factor-1 (IGF-1)

Actionable Ways To Increase Growth Hormone

  • Growth hormone is released in sleep: (1) need slow-wave/deep sleep; (2) need blood glucose to be relatively low – so try not to eat within two hours of sleep
  • Slow-wave/deep sleep mechanism to release growth hormone: delta wave activity stimulates the brain which stimulates the pituitary
  • Small doses of melatonin can increase growth hormone release: 500 micrograms can be beneficial in shifting pattern towards increased slow-wave deep sleep
  • Meditation can increase growth hormone release: 20 minutes of mediation per day can stimulate delta wave activity
  • Specifics of exercise to increase growth hormone release: weight lifting or endurance activity but must be limited to 60-75 minutes – (1) proper warm-up (literally warming body temperature) of about 10 minutes accelerates growth hormone release; (2) exercise hard but not to failure; (3) moderate blood glucose before and after exercise (no sugary energy drinks); (3) bring body temperature back down quickly
  • Exercise triggers the release of growth hormone and IGF-1 which positively impacts memory and cognition
  • Duration of exercise has sex-dependent effects on IGF-1: women could access the biggest peak of IGF-1 in the first 30 minutes of exercise; men needed 60 minutes to realize the peak of IGF-1
  • Sauna has a profound effect on decreasing cortisol and releasing growth hormone, increasing 16-fold (that’s 1,600%): (1) sauna between 176F-210F; (2) 20-30 minutes in duration then rapid cooling, repeat
    • If you don’t have a sauna you can wear plastics or sweats and jog to warm body

Supplements To Increase Growth Hormone

  • Arginine taken in pill form or IV: 3g -10g has been shown to increase growth hormone but there are diminishing returns above that range
  • In studies, Arginine raised growth hormone from 400-600% of baseline
  • Important side effects of arginine: (1) can’t combine arginine and exercise to double down – arginine will blunt effects of exercise for growth hormone; (2) arginine is a potent vasodilator which can be bad for those with cardiac or blood pressure concerns
  • Ornithine and L citrulline can also increase growth hormone but take vasodilation concerns seriously

Prescription Drugs

  • Most hormones we make have been synthesized and are available by prescription from a physician
  • Caution: anytime you inject something, you will shut down your own production of that hormone
  • Peptides: short sequences of amino acids that resemble hormones enough, they mimic the effect of the hormone in the body – some peptides change gene expression and set pathways for continued production of the hormone of interest
  • Peptides increase healing rates, weight loss, recovery, etc. and are used by actors, athletes, etc
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Notes By Maryann

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