Public Health

The Big Fat Lies Of Exercise

U.S. exercise docs were in a huff over the weekend, though it took a little digging to figure out why. Their opening salvo, in a Friday press release from the American College of Sports Medicine, began:

Are they dropping pounds or just revving their appetites?

Are they dropping pounds or just revving their appetites? iStockphoto.com hide caption

itoggle caption iStockphoto.com

"Leading experts in exercise and weight management have taken strong exception to assertions that exercise can inhibit weight loss by over-stimulating the appetite."

Huh? What assertions?

Though the press release never mentions any publication by name, apparently what had the fitness buffs hopping mad (stair-stepping mad?) was this week's Time cover story and ensuing blog buzz on the limits of exercise in curbing obesity.

In his story, "Why Exercise Won't Make You Thin," writer John Cloud quotes a Louisiana State University diabetes and exercise researcher Eric Ravussin as saying,

In general, for weight loss, exercise is pretty useless.

Them's fightin' words.

Cloud builds his story primarily around a recent study of 465 overweight, previously sedentary women who exercised for varying lengths of time each week for six months. All were specifically instructed not to change what they ate. In the end, although all groups lost two to five pounds on average, the group that exercised most (194 minutes per week) lost no more weight than those who didn't exercise at all.

But that's just one piece of research. The ACSM points to another recent study that tracked exercisers longer, and found that those who averaged a whopping 275 minutes a week had "the greatest amount of observed weight loss after 24 months." The ACSM concludes:

Exercise and diet go together. Weight management is most successful when careful attention is given to both physical activity and proper nutrition.

Well, right. That was Time's point, too. Talk about a tea-pot tempest.

The ACSM is worried that throwing even a little cold water on the rah-rah message that exercise burns fat will give fat folks another ill-founded reason to stay on the couch. And Time staffer John Cloud is worried that over-active gym-rats will incorrectly think that all those spin classes and pool-laps free them up to get doubles at the doughnut shop.

But we're adults. Most of us who have significantly thickened since high school really would like to slim down, and we can take this unvarnished truth: There is no calorie-free lunch.

Vigorous exercise is great for your heart, your mind, and your mood. (And recent research suggests that simply lowering stress may help deter the accumulation of belly fat — the unhealthiest sort.)

Exercise can also help you lose pounds and keep them off, just maybe not as many and not as quickly as you'd like. And it won't work at all if you eat more calories than you burn, which many of us Americans — exercisers and non-exercisers alike — tend to do.

Let's stop.

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