This episode I discuss metabolism and how our thyroid hormone and growth hormone control our metabolism. I also clarify that metabolism isn't just about burning energy, it’s about converting energy from different sources into fuels for building and repairing our tissues such as muscle, brain, and tendons and mobilizing energy from body fat storage. I discuss the role of iodine, selenium, and salt for thyroid health, and how specific exercise protocols, amino acids and temperature can dramatically shift levels of growth hormone release in waking and in sleep. I also describe the current landscape of prescription compounds, peptides and other factors for changing levels of thyroid and growth hormone, and some of their risks. Throughout the episode, mechanism and tools grounded in specific mechanisms are discussed. Thank you for your interest in science! Thank you to our sponsors: Four Sigmatic - http://foursigmatic.com/huberman Blinkist - http://blinkist.com/huberman Munk Pack - http://munkpack.com - Use code: huberman   Our Patreon page: https://www.patreon.com/andrewhuberman   Supplements from Thorne: http://www.thorne.com/u/huberman   Social: Instagram - https://www.instagram.com/hubermanlab Twitter - https://twitter.com/hubermanlab   Link to recent study on thermal stress and hormones: Endocrine Effects of Repeated Hot Thermal Stress and Cold Water Immersion in Young Adult Men. - https://pubmed.ncbi.nlm.nih.gov/33845653/   Timestamps: 00:00:00 Introduction 00:06:05 Thyroid & Growth Hormone 00:08:44 Food Shapes: Do They Matter? 00:11:43 Stevia: Naming & Impact 00:13:30 Metabolism 101: Your Brain the Furnace 00:17:33 Releasing Hormones From Your Brain, Stimulating Hormones from Your Pituitary 00:21:04 Thyroid Hormone’s Real Effects: Growth, Repair and Energy Consumption of Tissues 00:22:45 Iodine, L-Tyrosine & Selenium: The Trio Essential For Thyroid Function 00:26:05 How Much Iodine Do We Need? By Food, Supplement or Ocean Air 00:28:09 Selenium For Thyroid: Brazil Nuts & Other Valuable Sources 00:33:05 Selenium For Pregnancy, Prostate Cancer Risk, Acne 00:35:20 “Clean Eating” Downsides: Cruciferous Vegetables, Leeching Iodine 00:39:00 Other Benefits of Iodine: Reducing Inflammation 00:41:00 Why & How Increased Thyroid Increases Metabolism 00:42:12 What To Eat To Support Your Brain 00:43:00 Hyperthyroidism (Too Much) & Hypothyroidism (Too Little) 00:44:35 Menstruation: Thyroid Carbohydrate & Sugar Craving 00:45:33 Ketogenic Diet & Its Effects On Thyroid, Rebound Weight Gain 00:48:39 Growth Hormone: What, Why & How 00:51:18 Growth Hormone (GH) Changes Across The Lifespan & Risks of GH Therapy 00:53:40 How To Powerfully Increase Growth Hormone: Know The Natural Triggers 00:54:49 Not Eating Within 2hrs of Sleep: Keep Blood Glucose Low(ish) At Sleep 00:55:43 Delta Wave Brain Activity Is the Trigger For Growth Hormone Release 00:58:25 LOW Doses of Melatonin Supplementation For Increasing GH Release 01:01:00 Book: Altered Traits, Binaural Beats? Delta Waves Access 01:04:35 Specific Types & Duration of Exercise That Stimulate Growth Hormone & Warmups 01:08:40 Keeping Low Blood Glucose & Ensuring A Cool Down For Two Phase GH Release 01:10:36 Sex Differences For WHEN During Exercise Growth Hormone and IGF-1 Release Occurs: Males Have To Last Longer 01:14:10 Supplements That Increase Growth Hormone 100-400% (or more): Arginine, Ornithine 01:18:20 Arginine & Exercise Together Can Be Counter-Productive 01:19:50 L-Citrulline Better For Arginine Than Arginine Itself (?!); & Blood Pressure Caution 01:23:09 Growth Hormone Changes Across The Lifespan: No One Escapes 01:26:00 Heat (& Cold) for Triggering Extremely Large Increases In Growth Hormone 01:29:20 Specific Heat Protocols For Increasing Growth Hormone: Up To 16-Fold (?!) 01:34:30 2021 (New) Study: Heat Increases GH, & Lowers Cortisol, No Effects On Testosterone, DHEA Or Prolactin 01:36:00 Prescription Growth Hormone, & Emerging Peptides Therapeutics, Secretagogues Etc. 01:42