Huberman Lab
Essentials: Effects of Fasting & Time Restricted Eating on Fat Loss & Health
28 Aug 2025
In this Huberman Lab Essentials episode, I explore intermittent fasting and time-restricted eating, highlighting the positive benefits for weight loss, metabolism, organ health, circadian rhythms and cellular repair. I explain a practical framework for designing a time-restricted eating window that aligns with your lifestyle, exercise schedule and social schedule. I also cover what breaks a fast, how to support fasting with tools like salt intake and post-meal walks, and the use of fasting-related supplements, including berberine and metformin. Read the episode show notes at hubermanlab.com. Thank you to our sponsors AG1: https://drinkag1.com/huberman Carbon: https://joincarbon.com/huberman LMNT: https://drinklmnt.com/huberman Joovv: https://joovv.com/huberman Timestamps (00:00) Intermittent Fasting, Time-Restricted Eating (TRE) (00:50) Diet, Weight Loss, Calories & Hormones (05:50) Body’s Response to Eating vs Fasting, Fasting Duration (09:04) Sponsor: Carbon (10:50) Time-Restricted Feeding & Metabolic Benefits, Circadian Gene Rhythm (16:19) Optimal Meal Timing, Tool: Extend Sleep-Related Fasts (21:29) Sponsors: AG1 & LMNT (24:02) Eating Window Length, Tools: Adjusting TRE for Building Muscle, Regularity (26:55) Accelerate Transition to Fasting, Glucose Clearing, Tool: After-Meal Walk (28:36) Metformin, Berberine, Continuous Glucose Monitors; Cell Growth vs Repair, mTOR (31:46) Gut Microbiome; Transitioning to Intermittent Fasting & Individualization (34:03) Tool: 8-Hour Feeding Window & Weight Loss (35:25) Sponsor: Joovv (36:40) What Breaks a Fast?, Sugar; Tool: Using Salt to Support Fasting (39:42) Tool: Ideal Feeding Window Guidelines; Exercise & Social Considerations Disclaimer & Disclosures Learn more about your ad choices. Visit megaphone.fm/adchoices
Full Episode
Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health and performance. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine.
What we're going to talk about today is how intermittent fasting, AKA time-restricted feeding, impacts weight loss, fat loss in particular, muscle maintenance and loss and gain, organ health, such as gut health and liver health, the genome, the epigenome, inflammation, sickness, recovery, and healing from sickness, exercise, cognition, mood, and lifespan.
So let's talk about eating and what happens when you eat, and let's talk about fasting or not eating and what happens when you fast. If ever there was a topic that is controversial, especially on the internet, it is that of diet and nutrition. So I'm wading into this with a smile and in eager anticipation of all the, but, but, but this, and but, but that, and wait, but this showed that.
Here's the deal. We need to precisely define what it is that we're talking about when we talk about nutrition. I'm going to give you an example of a study that was published a few years ago, 2018, by a colleague of mine at Stanford, Chris Gardner. He's a terrific professor of nutrition and has done a lot of important studies on how nutrition impacts different aspects of health.
This paper, where Chris is the first author, it's Gardner et al, 2018, JAMA, looked at weight loss in people following one particular diet versus another particular diet. And this was a 12 month weight loss study. So it was focused specifically on weight loss, although they looked at some other parameters as well.
And the basic conclusion of the study was that there was no significant difference in weight change between people following a healthy low fat diet versus a healthy low carbohydrate diet with significantly more dietary fats in them.
This caused a lot of ripples in the world of nutrition and nutritional science, and certainly in the general population, because anyone that understands diet and nutrition would immediately say, but wait, there are all sorts of different implications of eating one type of diet, say low carbohydrate, higher fats, versus a higher carbohydrate, lower fat diet. And indeed there are.
This study was focused specifically on fat loss and on weight loss. So as we discuss time-restricted feeding, we need to be very precise about what are the effects of time-restricted feeding and of eating in particular ways at particular times. We are going to emphasize again, whether or not the study was done in mice or in humans, in athletes and men and women or both.
But the study from Gardner and colleagues is a beautiful study and really emphasizes that if one's main goal is simply to lose weight, then it really does not matter what one eats, provided that the number of calories burned is higher than the number of calories ingested. However,
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