One of the reasons cited for various government programs promoting healthy eating, including the “fat” or “fast food tax,” is the obesity epidemic in America. This is especially true for America’s youth, as childhood obesity is often cited as one of the nation’s greatest health risks.

And experts and bureaucrats alike point the finger at unhealthy diets and “junk food.” A recent study linked childhood obesity in New Zealand with “heavy promotion of calorie-laden junk foods in advertisements near high schools.”

Various public schools, under tighter financial pressures, have made deals with panies, and the backlash is starting to be felt, as soda, candy, and chips take the rap for kids’ growing waistlines.

The Simpsons, as usual a reliable pop culture bellwether, had an episode called “The Heartbroke Kid,” in which Bart es addicted to junk food at his elementary school, gets fat, and has multiple heart attacks. The vending machines feature such “hip” treats as “Lollapalollipops,” “Krishna Krisps,” and “Dalai Lamanade.” Ingredients in one snack, as Lisa observes, include “monosodium poisonate and partially deweaponized plutonium.”

But have we been too quick to judge the root causes of childhood obesity? Duane D. Freese at Tech Central Station observes that

On the same day that the Federal Trade Commission finished a two day conference on food marketing and obesity and a couple days after the activist group Center for Science in the Public Interest called for warning labels on non-diet soda pop, up popped a study by scientists at the University of New Mexico that said most of the talk was so much hot air.

While scapegoating fast food and vending panies has been a favorite pastime for nutrition experts, more important contributing factors to childhood obesity have been overlooked. The greatest of these is perhaps the lack of childhood exercise. The New Mexico study provided a glimpse at what is going on in the real world. The researchers tracked changes in body mass index, skin fold, physical activity and eating habits of 2,200 girls in three cities for 10 years, from age nine to 19.

The results? Even as eating remained the same, the rate of excess weight and obesity doubled among girls whose physical activity had markedly declined.

In other words, fast food and soft drinks weren’t the culprits. Neither was advertising of it. It was a decline in exercise that mattered. Just two to five hours of brisk walking a week — 17 to 43 minutes a day — would prevent girls gaining 9 to 20 pounds, according to the study. And even if it didn’t prevent weight gain, the additional exercise likely would make the girls healthier and feel better than all the dieting ing out of Washington conferences in events.

The sedentary lifestyle of children (and adults) is clear in this country. Wealth and technology, along with substandard physical education, bined to make physical inactivity a favorite pastime.

My experience with P.E. growing up supports this. On days when P.E. was indoors, the teachers would roll out a few basketballs, and those who wanted to play would, and the others would sit and talk and watch. On outdoor days, we’d stroll lazily around the track. And even this little bit of exercise is minimized, since health class, which consists of sitting in a classroom, is bined with P.E.

Things aren’t much better when kids get home, because there’s TV to watch, video games to play, and safety concerns with letting kids “go out and play.” Instead of so vigorously attacking fast food and “junk panies, people concerned about the health of children should emphasize the importance of regular exercise and physical activity.