This article is an excerpt from the Shortform book guide to "The Obesity Code" by Jason Fung. Shortform has the world's best summaries and analyses of books you should be reading.
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Does intermittent fasting work for obesity? How long should you fast to induce weight loss?
According to Canadian nephrologist Jason Fung, intermittent fasting is the key to beating obesity. Intermittent fasting is an eating pattern wherein you intentionally stop eating for a stretch of time. Research has shown that regular fasting reduces insulin resistance, lowering your set weight and allowing you to steadily lose fat.
Here’s how intermittent fasting can help you put an end to obesity once and for all.
Intermittent Fasting and Weight Loss
In the short term, most diets produce weight loss. However, dieting alone can’t fix obesity, because dieting doesn’t lower your set weight. Once you fall beneath that set weight, your body will compel you to eat and regain any weight you’ve lost.
According to Jason Fung, intermittent fasting in combination with a healthy diet can heal insulin resistance, which is at the heart of obesity. Fung explains that when you fast beyond 24 hours, insulin levels fall and your body begins to derive energy from your stored glycogen and fat. Beyond two to three days, ketosis kicks in: Fat becomes your body’s main energy source, producing three energy molecules—glucose, fatty acids, and ketones—that fuel your body and brain. (Shortform note: Stephens calls ketosis your “fat-burning superpower,” and she encourages people to embrace fasting as an enjoyable lifestyle rather than self-deprivation. In Stephens’s view, the benefits of fasting vastly outweigh not eating as often—and she says that in time, you won’t even want to eat all the time.)
(Shortform note: In Fast. Feast. Repeat., Gin Stephens explains that long-term dieting causes “diet brain,” a mindset condition wherein you become disillusioned with dieting as a solution to weight loss. She agrees with Fung that intermittent fasting is the solution to obesity—specifically, she recommends Alternate-Day Fasting and suggests trying various lengths until it feels right for you. While Stephens is not a health professional, she’s run several online support groups that have helped thousands of people overcome obesity.)
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Here's what you'll find in our full The Obesity Code summary :
- Why everything we were taught about obesity is wrong
- The theory of obesity as a hormonal disorder that causes overeating
- Why dieting doesn’t work and exercise actually has little impact on weight loss
