With Teen Obesity, Inactivity Is Only Part of the Problem

I panic every time I see another "exercise doesn't work!" story — until I read between the lines and learn once again that exercise is a good thing. On the heels of its conversation-starting cover story on the exercise "myth," Time is tackling a new study of teen obesity that claims inactivity is only partly to blame for heavier kids.

Obesity rates in teenagers have triple between 1976 and 2004, with lack of exercise the suspected culprit. But a new report published in Obesity Reviews says that physical activity levels among teens have actually stayed fairly steady. So does that mean that exercise doesn't matter? Hardly, so read more.

Unfortunately, this latest study only looked at activity levels, not eating habits, and the participants were self-reporting on their own habits, which can lead to unreliable data. These figures merely suggest that the increase in teen obesity can't be explained away by teens' lack of exercise, according to Dr. Youfa Wang, the lead author of the study. Here's more:

So does this mean that exercise isn't important in controlling weight? As tempting as that conclusion might be, Wang and other health experts say that's not exactly what the new data show. . . . While exercise may not contribute directly to weight loss, it is critical for maintaining a healthy weight, since it helps calibrate the balance between energy taken in and energy burned off. "The data is too gross, and too general, to assume that [exercise doesn't count]," warns Dr. Janet Walberg Rankin, a professor in the department of human nutrition, foods, and exercise at Virginia Tech. "We need to have a dual approach to weight involving both activity and diet. I would hate for people to take away from this study that activity has nothing to do with weight."

Phew! Thanks, doc. I also hope that's not what people take away from this study. In fact, to me, it says the opposite. If teen obesity is going up because teens have increased their calorie intake without increasing their activity levels, then that seems to say pretty clearly that exercise does make a difference. Do you agree?

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