This episode I discuss the science and practice of fasting, also called time-restricted feeding. I review the data on how limiting food intake to specific portions of every 24-hour cycle (or fasting longer) impacts weight loss, fat loss specifically, liver health, mental focus, muscle, longevity and more. I explain how "fasted" is contextual, and relates to blood glucose levels and their downstream effects, and how the depth of fasting can be adjusted with behaviors such as different types of exercise, or with glucose disposal agents. I also discuss the optimal fasting protocol: and both the absolute (non-negotiable) and variable (contextual) features of a fasting/time-restricted-feeding protocol that will allow you to get the most benefits. I also discuss what does and does not break a fast, the effects of fasting on hormones like testosterone and cortisol and on fertility. I also review how different feeding windows of 8 or 10 or 4 hours differentially impact the effects of fasting, and why the classic 8 hour feeding window came to be, but also might be ideal. I discuss mechanisms and offer tools to discern the optimal fasting duration and timing for you.   Thank you to our sponsors: ROKA - https://www.roka.com -- code: "huberman" InsideTracker - https://www.insidetracker.com/huberman Helix Sleep - https://www.helixsleep.com/huberman    RETHINK EDUCATION: The Biology of Learning Featuring Dr. Andrew Huberman https://youtu.be/Oo7hQapFe3M   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 Facebook - https://www.facebook.com/hubermanlab  Website - https://hubermanlab.com Newsletter - https://hubermanlab.com/neural-network    Links: Comprehensive Review On Fasting In Humans: doi: 10.1210/endrev/bnab027   Timestamps: 00:00:00 Introduction, Blood Glucose & Mortality, Mice Vs. Humans 00:06:02 Sponsors: Roka, InsideTracker, Helix 00:09:42 Neuroplasticity Protocols & Online Lecture youtube.com/results?search_query=logitech+Huberman 00:11:20 Feeding, Fasting, Performance 00:13:50 Calories-In, Calories-Out (CICO); Perfect Diets 00:19:48 Feeding-Induced Health Conditions  00:25:33 Time Restricted Eating: When We Eat Is Vital 00:29:45 The Eight Hour Feeding Window  00:31:26 Feeding Deep Into the Night Is Bad (In Humans) 00:36:33 Liver Health 00:39:45 Time Restricted Feeding Protocol: Rules 00:41:35 When to Start & Stop Eating 00:45:38 Gastric Clearance, Linking Fasting to Sleep & 00:52:35 Effects of Specific Categories of Food 00:55:40 Precision In Fasting: Protocol Build 00:59:30 4-6 Hour Feeding Windows 01:03:08 Protein Consumption & Timing for Muscle 01:08:13 How to Shift Your Eating Window 01:13:20 Glucose Clearing, Exercise & Compounds 01:22:37 Blood Glucose: Monitoring, mTOR & Related Pathways 01:27:40 Gut Health: Fasting, Clock Genes and Microbiota 01:29:15 Non-Alcoholic Fatty Liver  01:32:00 Effects of Fasting on Hormones: Testosterone, Cortisol 01:38:40 Fertility 01:41:50 8-Hour Feeding Window: Weight Loss Without Calorie Counting 01:43:20 Eating Every-Other-Day  01:45:29 Adherence 01:47:15 Mental Focus & Clarity 01:49:12 Enhancing Weight Loss from Body Fat: Hepatic Lipase 01:53:15 What Breaks a Fast? Rules & Context 01:58:50 Artificial Sweeteners, Plant-Based Sweeteners 02:01:42 Glucose Clearing II, Cinnamon, Acidity, Salt 02:06:42 My Circadian Clock, Zero-App  02:08:20 Odd (But Common) Questions 02:09:23 Effects of Sauna & Dehydration on Blood Glucose 02:11:12 The Ideal Fasting Protocol  02:24:00 More Resources, Ways to Support Us, Supplements Please note that The Huberman Lab Podcast is distinct from Dr. Huberman's teaching and research roles at Stanford University School of Medicine. The information provided in this show is not medical advice, nor should it be taken or applied as a replacement for medical advice. The Huberman Lab Podcast, its