A long-term study of the rock stars of dieting — contestants on the reality TV show “The Biggest Loser” — reveals some of the reasons why it is hard to keep the pounds off, says the New York Times. Metabolic rates slow down during dieting and remain low for years afterward. At the same time, reduced levels of the hormone leptin induce a perpetual hunger. “Obesity research has consistently shown 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,” says the Times.
The metabolism of the contestants was dramatically slower after their diets ended. One of them, Danny Cahill, regained 100 pounds, to weigh 295 pounds, and burns 800 fewer calories a day than would be expected for someone his weight. Kevin Hall, an expert on metabolism at the National Institute of Diabetes and Digestive and Kidney Diseases, said “I am just blown away” by the biological persistence of the body to be a particular weight. “It is frightening and amazing.”