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)
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
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 (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
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)
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
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
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