Why do those who lose a dramatic amount of weight often gain much or all of it back? It’s a question of great interest to the scientific community, and a popular NBC reality show may have some insight into the matter. In a discouraging but nevertheless worthwhile New York Times article, journalist Gina Kolata discusses what researcher Kevin Hall found when he decided to track the progress of contestants from season eight of The Biggest Loser. In the show, contestants embark upon a rigorous program of diet and exercise, sometimes shedding hundreds of pounds in the process. It makes for compelling TV, but the show’s triumphant contestants struggle mightily to maintain their newly svelte forms. The six Loser contestants profiled in Kolata’s article, including season-eight champ Danny Cahill, have all gained some of the weight back, and a few are even heavier than when they started. But viewers should not assume this is due to a lack of discipline or willpower on the part of the contestants, the experts say. It turns out that the human body sabotages weight loss in a number of important ways.
A key factor in regaining weight, the article reveals, is resting metabolism, i.e., the amount of calories a person burns while not doing anything. When the contestants embarked upon the gauntlet that is The Biggest Loser, they had what the article describes as “normal metabolisms.” But their metabolic rates dropped dramatically after they lost a huge percentage of their body weight. And their metabolism did not recover in the years following the show. In order to keep the weight off, contestants have to eat dramatically less than a normal human being would. “Anything more turns to fat,” Kolata writes. Another pitfall is a hormone called leptin, which controls hunger. The contestants on The Biggest Loser found that their leptin levels also plummeted when they lost weight. As one doctor grimly puts it: “The only way to maintain weight loss is to be hungry all the time.” The article is careful to point out that long-term weight loss is not impossible, just extremely difficult. The body works against it at every available opportunity. That‘s just biological reality, even for contestants on The Biggest Loser.