The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting

by Jason Fung

Insulin is a fat-storage hormone. When we eat, insulin increases, signaling our body to store some of this food energy as fat for later use. It’s a natural and essential process that has helped humans survive famine for thousands of years, but excessively and persistently high insulin levels result inexorably in obesity. Understanding this leads naturally to a solution: if excessive insulin is causing obesity, then clearly the answer lies in reducing insulin. Both the ketogenic diet (a low-carb, moderate-protein, high-fat diet) and intermittent fasting are excellent methods of reducing high insulin levels.

The cause of obesity!