Weighing the Evidence on Exercise New York Times
But a growing body of science suggests that exercise does have an important role in weight loss. That role, however, is different from what many people expect and probably wish. The newest science suggests that exercise alone will not make you thin, but it may determine whether you stay thin, if you can achieve that state. Until recently, the bodily mechanisms involved were mysterious. But scientists are slowly teasing out exercise’s impact on metabolism, appetite and body composition, though the consequences of exercise can vary. Women’s bodies, for instance, seem to react differently than men’s bodies to the metabolic effects of exercise. None of which is a reason to abandon exercise as a weight-loss tool. You just have to understand what exercise can and cannot do.
“In general, exercise by itself is pretty useless for weight loss,” says Eric Ravussin, a professor at the Pennington Biomedical Research Center in Baton Rouge, La., and an expert on weight loss. It’s especially useless because people often end up consuming more calories when they exercise. The mathematics of weight loss is, in fact, quite simple, involving only subtraction. “Take in fewer calories than you burn, put yourself in negative energy balance, lose weight,” says Braun, who has been studying exercise and weight loss for years. The deficit in calories can result from cutting back your food intake or from increasing your energy output — the amount of exercise you complete — or both. When researchers affiliated with the Pennington center had volunteers reduce their energy balance for a study last year by either cutting their calorie intakes by 25 percent or increasing their daily exercise by 12.5 percent and cutting their calories by 12.5 percent, everyone involved lost weight. They all lost about the same amount of weight too — about a pound a week. But in the exercising group, the dose of exercise required was nearly an hour a day of moderate-intensity activity, what the federal government currently recommends for weight loss but “a lot more than what many people would be able or willing to do,” Ravussin says.
.jpg)
Many times, the elimination of "junk" foods, the reduction of portion sizes, and the incorporation of exercise into your daily activities make very cost-effective and lasting differences in weight control. Denise Reynolds, RD LD/N is an Examiner from
