Nutrition Action Healthletter
Jan/Feb 2000 — U.S. Edition 


 
Exploding Ten Exercise Myths


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4
Exercise burns lots of calories.

“People have the mistaken idea that exercise is a fabulous way to lose weight,” says William Evans of the University of Arkansas for Medical Sciences. “But exercising doesn’t burn a lot of calories.”
   Walking or running a mile burns about 100 calories. But sitting still for the same time burns about 50 or 60 calories. “So the extra you expend isn’t huge and people get discouraged at their slow rate of weight loss.”
   Another misconception: You keep burning considerably more calories for a long time after you stop exercising. “Calorie expenditure is elevated for the first minute or two, but by five or six minutes the extra expenditure is pretty small, and by 40 minutes post-exercise, it’s back to where you started,” says Evans.
   That doesn’t mean dieters should give up on exercise. The more you exercise, the more fit you’ll get. That means you’ll burn more calories because you can walk briskly or run for five miles instead of one. So instead of burning 100 calories, you burn 500 (that’s 250 more than if you had stayed on the couch).
   What’s more, says Evans, “the better-conditioned you are, the more fat you burn for energy, because your muscles adapt to using an enzyme that oxidizes fat. People who are less-trained burn more carbohydrate instead.”
   Dieters who exercise also lose less lean body mass — that is, less muscle — than dieters who just cut calories. And physical activity can help with the toughest problem: keeping weight off.
   Says Evans: “Studies show that after people lose weight, the best predictor of maintaining the weight loss is whether they exercise regularly.”

Illustrations: Loel Barr

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