When the show began, the contestants, though hugely overweight, had normal metabolisms for their size, meaning they were burning a normal number of calories for people of their weight. When it ended, their metabolisms had slowed radically and their bodies were not burning enough calories to maintain their thinner sizes.
As he regained more than 100 pounds, his metabolism slowed so much that, just to maintain his current weight of 295 pounds, he now has to eat 800 calories a day less than a typical man his size. Anything more turns to fat.
Their experience shows that the body will fight back for years.
“As long as you are below your initial weight, your body is going to try to get you back.”
But what obesity research has consistently shown is that dieters are at the mercy of their own bodies, which muster hormones and an altered metabolic rate to pull them back to their old weights, whether that is hundreds of pounds more or that extra 10 or 15 that many people are trying to keep off.
“There are no doubt exceptional individuals who can ignore primal biological signals and maintain weight loss for the long term by restricting calories,” he said, but he added that “for most people, the combination of incessant hunger and slowing metabolism is a recipe for weight regain — explaining why so few individuals can maintain weight loss for more than a few months.”
“The difficulty in keeping weight off reflects biology, not a pathological lack of willpower affecting two-thirds of the U.S.A.,” he said.