You know that your metabolism slows a bit when you lose weight, but recent research has shed light on just how badly your body wants to get back to its original size. When contestants from season 8 of
The Biggest Loser were put through a battery of health tests six years after their season ended,
researchers found that their metabolisms were incredibly sluggish, despite the fact that they'd regained two-thirds of the weight, on average (larger people
burn more calories, even at rest). In fact, they were burning about 500 fewer calories per day than the researchers expected. "This metabolic slowing seems to continue as long as your weight is lower than where you started," says lead study author Kevin Hall, PhD, a metabolism expert at the National Institute of Diabetes and Digestive and Kidney Diseases, in Pittsburgh. Of course,
Biggest Loser contestants are going to extremes to shed pounds, and Hall notes that the average person probably wouldn't have such a drastic metabolism slowdown. "More on the line of maybe 100 calories per day, as opposed to 500," he says. "But you're still fighting a biological drive to regain the weight."
The Takeaway: You'll need to carefully track your calories-in, calories-out if you want to prevent your weight from creeping back up, and stay consistent with it. "The one contestant who kept the weight off despite having a slower metabolism changed her lifestyle dramatically and made fitness an integral part of her day to day activity," says Hall.
