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.  For the full show notes, visit hubermanlab.com. Thank you to our sponsors AG1 (Athletic Greens): https://athleticgreens.com/huberman LMNT: https://drinklmnt.com/huberman Thesis: https://takethesis.com/huberman Supplements from Momentous https://www.livemomentous.com/huberman Timestamps (00:00:00) Introduction, Blood Glucose & Mortality, Mice Vs. Humans (00:06:18) Sponsors: AG1, LMNT, Thesis, Momentous (00:09:42) Neuroplasticity Protocols & Online Lecture (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 Title Card Photo Credit: Mike Blabac Disclaimer