No, according to an article in New York magazine entitled “The Scientist and the Stairmaster.”

Just last month, the American Heart Association and the American College of Sports Medicine published joint guidelines for physical activity and health. They suggested that 30 minutes of moderate physical activity five days a week is necessary to “promote and maintain health.” What they didn’t say, though, was that more physical activity will lead us to lose weight. Indeed, the best they could say about the relationship between fat and exercise was this: “It is reasonable to assume that persons with relatively high daily energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures. So far, data to support this hypothesis are not particularly compelling.” In other words, despite half a century of efforts to prove otherwise, scientists still can’t say that exercise will help keep off the pounds.

 Ah hah!  I knew it all along!  Of course, there is the whole thing about…

We may increase our overall fitness; we may live longer, perhaps by reducing our risk of heart disease or diabetes; we’ll probably feel better about ourselves. But there’s no reason to think that we will lose any significant amount of weight, and little reason to think we will prevent ourselves from gaining it.

Doh!  Live longer, reduce our risks… there’s always a catch, isn’t there.