Exercise brings many health benefits but its stand-alone effects on weight loss are less than some have claimed.
“The message of our work is really simple,” although not agreeable to hear, Melanson said. “It all comes down to energy balance,” or, as you might have guessed, calories in and calories out. People “are only burning 200 or 300 calories” in a typical 30-minute exercise session, Melanson points out. “You replace that with one bottle of Gatorade.”
This does not mean that exercise has no impact on body weight, or that you can’t calibrate your workouts to maximize the amount of body fat that you burn, if that’s your goal.“If you work out at an easy intensity, you will burn a higher percentage of fat calories” than if you work out a higher intensity, Carey says, so you should draw down some of the padding you’ve accumulated on the hips or elsewhere — if you don’t replace all of the calories afterward. To help those hoping to reduce their body fat, he published formulas in The Journal of Strength and Conditioning Research last month that detailed the heart rates at which a person could maximize fat burning. “Heart rates of between 105 and 134” beats per minute, Carey said, represent the fat-burning zone. “It’s probably best to work out near the top of that zone,” he says, “so that you burn more calories over all” than at the extremely leisurely lower end.
Perhaps just as important, bear in mind that exercise has benefits beyond weight reduction. In the study of obese people who took up exercise, most became notably healthier, increasing their aerobic capacity, decreasing their blood pressure and resting heart rates, and, the authors write, achieving “an acute exercise-induced increase in positive mood,” leading the authors to conclude that, “significant and meaningful health benefits can be achieved even in the presence of lower than expected exercise-induced weight loss.”
