How to Control Your Metabolism by Thyroid & Growth Hormone | Huberman Lab Essentials

This Huberman Lab Essentials episode covers the two hormone systems Huberman argues most strongly set overall metabolism: thyroid hormone and growth hormone. He walks through the brain-pituitary-gland signaling chain, explains what T3 and T4 do, and details the nutrients needed for healthy thyroid function: iodine, selenium, and L-tyrosine. For growth hormone, he describes how it is released during early slow-wave sleep and how exercise, low blood glucose, arginine, body temperature, and sauna can dramatically increase it. He also touches on the age-related decline in growth hormone and the emerging, riskier world of peptides like sermorelin.

• Sauna (20 min hot, 30 min cooling, 20 min hot, repeated over three days) has been shown to increase growth hormone release up to 16-fold (1600%).
  00:24:53
• Resistance or endurance exercise of ~60 minutes can raise growth hormone 300-500%, both immediately and the following night.
  00:18:09
• Arginine, by mouth or vein, can boost growth hormone 400-600% above baseline, but more than ~9 grams actually blunts the effect.
  00:20:43
• Combining arginine with exercise does NOT stack: growth hormone stays clamped around 300-500% instead of adding up.
  00:20:43
• Eating within two hours of sleep suppresses growth hormone release because elevated insulin and glucose block it.
  00:13:29
• Between ages 30 and 40 nightly growth hormone output drops two- to three-fold, but exercise and sleep habits can fully offset the decline.
  00:21:45
• Huberman warns that excess heat is genuinely dangerous; it doesn't take much of a brain temperature rise to kill neurons and cause death from hyperthermia.
  00:24:22

• You can basically forget about T4; T3 is the more active thyroid hormone.
  00:03:05
• Brazil nuts are the 'heavyweight champion' for selenium: six to eight contain about 550 micrograms.
  00:06:11
• Recommended daily selenium varies by country, averaging around 155 micrograms; most people don't get enough.
  00:05:41
• Growth hormone is released in the early part of sleep during slow-wave (deep) sleep, gated by delta-wave brain activity.
  00:13:29
• Certain meditation can put the brain into states that mimic slow-wave sleep, potentially aiding growth hormone release.
  00:16:08
• A sugary sports drink during exercise immediately flatlined growth hormone levels in studies.
  00:18:40
• A proper ~10-minute warm-up that actually warms the body helps maximize the growth hormone response to exercise.
  00:17:39
• Too-high growth hormone grows all tissues, including heart, lungs, liver, and spleen, which is the danger of abuse.
  00:11:59
• Continuously injected peptides can switch on long-lived gene expression programs that may even feed tumor growth.
  00:29:00

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