The Obesity Code: Unlocking the Secrets of Weight Loss (Why Intermittent Fasting Is the Key to Controlling Your Weight)

by Jason Fung

The theory of obesity that’s been dominant for the last half century—that excess calories inevitably lead to obesity—the theory that’s assumed to be unassailably true, was simply not true. None of it was true. And if excess calories don’t cause weight gain, then reducing calories won’t cause weight loss. THE BODY SET WEIGHT YOU CAN TEMPORARILY force your body weight higher than your body wants it to be by consuming excess calories. Over time, the resulting higher metabolism will reduce your weight back to normal. Similarly, you can temporarily force your body weight lower than your body wants it to be by reducing calories. Over time, the resulting lowered metabolism will raise your weight back to normal. Since losing weight reduces total energy expenditure, many obese people assume that they have a slow metabolism, but the opposite has proved to be true.8 Lean subjects had a mean total energy expenditure of 2404 calories, while the obese had a mean total energy expenditure of 3244 calories, despite spending less time exercising. The obese body was not trying to gain weight. It was trying to lose it by burning off the excess energy. So then, why are the obese . . . obese? The fundamental biological principle at work here is homeostasis. There appears to be a “set point” for body weight and fatness, as first proposed in 1984 by Keesey and Corbett.9 Homeostatic mechanisms defend this body set weight against changes, both up and down. If weight drops below body set weight, com...