Tacking regular exercise onto a diet program typically doesn’t help obese children lose more weight, a new review suggests.

“Changing diet, improving diet, reducing calories is enormously important for weight loss both in kids and adults,” said Gary Bennett, who studies obesity prevention at Duke University but wasn’t involved in the new report. “Exercise is important, too, but I think we sometimes overemphasize how important exercise is.”

Researchers analyzed 14 trials that assigned overweight and obese youth to a diet and exercise program or a diet-only plan.

Most studies found that kids tended to have a lower body mass index and a smaller percentage of body fat after completing either type of intervention. Adding aerobic exercise such as jogging or dance to a restricted-calorie diet had little effect on weight loss.

However, kids who did resistance training lost more body fat than those who didn’t exercise. Strength training was tied to an extra drop in body fat and a greater increase in muscle.

The reviewers found that some measures of cholesterol and blood sugar, including insulin and ”good” cholesterol, improved with the addition of regular exercise. But changes in other levels, such as “bad” cholesterol, were greater with a diet plan alone.

In many studies, kids regained weight once the programs ended.

— Reuters