The genetic limits of obesity.

Good news: Child obesity in the United States has stopped increasing. Government data analyzed in the Journal of the American Medical Association tell the story. According to a New York Times summary, "in 1980, 6.5 percent of children age 6 to 11 were obese, but by 1994 that number had climbed to 11.3 percent. By 2002, the number had jumped to 16.3 percent, but it has now appeared to stabilize around 17 percent."

Experts are jubilant. Here's the Washington Post:

"This lets us know that the epidemic is not an unstoppable epidemic and gives us hope our collective work can reverse it," said Risa Lavizzo-Mourey, president and chief executive of the Robert Wood Johnson Foundation, a private nonprofit group that helps fund anti-obesity programs. "It tells us that when we all work together—parents and schools, government, voluntary organizations, industry—we can make a difference."

The Associated Press reports similar excitement:

Dr. Reginald Washington, a children's heart specialist in Denver and member of an American Academy of Pediatrics obesity committee, said "the country should be congratulated" if the rates have in fact peaked. "There are a lot of people trying to do good things to try to stem the tide," Washington said. Some schools are providing better meals and increasing physical education, and Americans in general "are more aware of the importance of fruits and vegetables," he said.

But wait: There's a problem. The stabilization may not be due to remedial interventions. According to the Times and other papers,

One concern is that the lull could represent a natural plateau that would have occurred regardless of public health efforts. "It may be that we've reached some sort of saturation in terms of the proportion of the population who are genetically susceptible to obesity in this environment," Dr. Ogden [the study's lead author] said. "A more optimistic view is that some things are working."

Bummer, huh? All that work we've been doing to teach healthy eating and exercise habits—irrelevant? Is the leveling off in child obesity just a product of genetic exhaustion?

I sure hope so.

I don't mean to dismiss the importance of changing habits. We'll need every bit of those changes to drive obesity back down to 1980 levels. But when you hear talk of making the world a better place, don't underestimate how much worse things can get. Job number one is to halt the frightening increase in fat. And the strongest ally we could ask for in holding that line isn't effort or education. It's genetics.