Magazine article Consumers' Research Magazine

Exercise Is Not a Major Player in Weight Loss, but It Helps Prevent Weight Gain

Magazine article Consumers' Research Magazine

Exercise Is Not a Major Player in Weight Loss, but It Helps Prevent Weight Gain

Article excerpt

It looked more like a rock concert than a scientific colloquium. Every seat was occupied, many by young people wearing shorts and colorful shirts. The aisles were full of standing enthusiasts, and they flowed from the back of the room through the doors into the hall. Dozens more sat on the floor in front of the seats, many in positions from which there was no way they could see the slides.

The place was the Minneapolis Convention Center; the event was the Annual Meeting of the American College of Sports Medicine; and the superstar was Jack Wilmore, professor in the Department of Kinesiology and Health Education at the University of Texas at Austin. Wilmore is one of the elder statesmen of exercise physiology, and he has trained Ph.D.s from coast to coast.

Wilmore's receding hair is near-white, but he still has the lean look and easy stride of the runner he has been for many years. His topic was "Exercise and Weight Control: Misconceptions, Gadgets, Gimmicks, and Quackery." If this seductive title was not enough, the word was out that Wilmore had something new to say. He had the audience in the palm of his hand, he knew it, and he piled it on with his tantalizing opening: "I'm going to shock you. I've changed my mind. I'm going to say something I would not have believed a couple of years ago."

Then he dropped the other shoe. "Exercise is not a major player in weight loss." He paused, and added (as though he sensed his audience needed a consolation award), "But it is the number one player in preventing weight gain."

Magazines carry advertisements for exercise machines that emphasize their fat-burning virtues. Shapely young people in television fitness shows urge you to use their routines to burn fat. Public health professionals emphasize that exercise must be the keystone of a weight loss program. Now, one of our most respected exercise physiologists seems to be telling us, in the words of Willard Robison's jazz classic, "T'aint so, honey, t'aint so."

What goes on? Are we preparing for blinding insight from new studies and a grand revision of old ones? Not really. What Wilmore has done is recognize that many of our beliefs about exercise and weight loss are based on anecdotal accounts; but a review of published data showed results to be variable. One study reports a loss of five pounds of fat per week, which surely looks signifificant. But others record 1.4, 0.8, and even 0.04 pounds of fat per week. There are also studies reporting a gain in weight during exercise programs, and not only from muscle-building programs such as weight-lifting; some walkers gained 0.7 pounds per week.

For all studies combined, Wilmore calculated the annual weight loss averaged a little less than six pounds of fat. This is not enough to help overweight people significantly; and, in any case, most of the people studied discontinued exercise after the program ended.

The point usually forgotten is that, even if you exercise regularly, you burn most of your fat when you are not exercising. Furthermore, when you do exercise you burn much less fat than the exercise gurus would have you believe. Put these together, and the amount of fat you lose during exercise is much less than most folks imagine.

A 150-pound body needs 1,500 calories a day to maintain resting metabolism (about 10% more for a man). The activities connected with a sedentary job add another 40% to 50%, or about 675 calories, which boosts the total to about 2,175 per day.

If you exercise conscientiously, you might run 20 miles a week or do an equivalent amount of other exercise to burn an average of 285 calories a day.

How are these calories divided? At rest, you burn about two-thirds fat and one-third carbohydrate. Even a sedentary job involves movement, such as walking, picking up the phone, or working at a desk, and then there are chores at home. Movement burns less fat and more carbohydrate. We cannot know how much, but let's assume that overall, resting and working, the ratio of fat to carbohydrate is 50/50. …

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