The Flatness of Fatness

The prevalence of obesity among American women, and possibly among men as well, seems to have reached a plateau, according to a CDC analysis of the latest data from the National Health and Nutrition Examination Survey (NHANES). Overall, the share of American adults who are considered obese, meaning they have body mass indexes of 30 or more (equivalent to a weight of 203 pounds or more for a man who is five feet, nine inches tall), has more than doubled since the late 1970s, when it was about 15 percent. But the rate for women, which was 35 percent in the 2005-06 NHANES, has not increased significantly since 1999, while the rate for men was 33 percent in 2005-06, the same as in the 2004-05 survey. Fat warrior Kelly Brownell, who has repeatedly predicted that the current generation of children will have shorter life spans than their parents because they're so damned fat (even though there's no evidence to support that prediction), grudgingly concedes that the latest NHANES numbers are sorta good news, telling New York Times science reporter Gina Kolata:

There is slight joy in fact that the number has not increased since 2003. But it is mainly discouraging news that the number has not gone down at all.

Madelyn Fernstrom, director of the weight management program at the University of Pittsburgh Medical Center, has a different perspective:

She said there might be more to it than people finally reaching the limit of how fat they can get.

Instead, Dr. Fernstrom said, many Americans are setting more rational weight goals and discovering that even if they cannot lose much weight, they can try to avoid gaining.

The national goal of no more than 15 percent of Americans being obese is "unrealistic," she said, even counterproductive. And the so-called normal weight defined as a body mass index, or B.M.I., of 18 to 25 is impossible for many people to maintain.

"When the bar is set too high, people do nothing," Dr. Fernstrom said. "Whether it's 7 to 10 fruits and veggies a day when people can't even get to 5, or 75 minutes of physical activity when 20 is hard for most people, or a B.M.I. under 25."

As I noted in a recent column, the scientific basis for setting the preferred BMI range at 18 to 25 is questionable, since people in the "overweight" (but not obese) category have the lowest mortality rates. And as Kolata points out in her book Rethinking Thin, it's not clear that people who lose weight become healthier as a result of shedding pounds, as opposed to the lifestyle changes that go along with it. Look for my review of Kolata's book in the January issue of reason.

Is it only a coincidence that obesity's upward trend has leveled off around the same time as the downward trend in smoking? Maybe, although smoking is associated with lower weight, probably because it curbs appetite, quickens metabolism, and/or serves as an alternative form of oral gratification. Still, the health risks posed by a pack-a-day cigarette habit seem to be quite a bit worse than the health risks associated with being "overweight," although you might not guess that from listening to anti-fat alarmists like Kelly Brownell.