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);