Exercise reduces appetite, burnd fat

Exercise helps prevent weight regain after dieting by reducing appetite and burning fat before burning carbohydrates, U.S. researchers have learned.

Researchers at the University of Colorado Denver also found that exercise prevents the increase in fat cells that occurs during weight regain. This finding challenges the conventional wisdom that the number of fat cells is set and cannot be altered by dietary or lifestyle changes.

Paul S. MacLean and colleagues had obesity-prone rats eat as much as they wanted of a high-fat diet for 16 weeks and remained sedentary. Then for two weeks, the animals ate a low-fat and low-calorie diet, losing about 14 percent of their body weight. The rats maintained the weight loss by dieting for eight more weeks. Half the rats exercised regularly on a treadmill during, while the other half remained sedentary.

In the final eight weeks — the relapse phase of the study — the rats stopped dieting and ate as much low-fat food as they wanted. Some of the rodents exercised and some were sedentary during the period.

Compared with the sedentary rats, the exercisers regained less weight during the relapse period, burned more fat early in the day and more carbohydrates later in the day, accumulated fewer fat cells, accumulated less abdominal fat and reduced the drive to overeat.

The findings are published in the American Journal of Physiology — Regulatory, Integrative and Comparative Physiology.