The authors of the study, published in the Feb. 26 issue of the Journal of the American Medical Association, report that many preventive health programs and efforts have been launched by the government in recent years to combat the obesity epidemic in the United States.
These include new food labeling measures by the U.S. Department of Agriculture, as well as state and community programs sponsored by the CDC, and First Lady Michelle Obama's Let's Move program.
Even so, the overall numbers haven't inched down. In fact, obesity prevalence ticked up in women 60 and older, from less than 32 percent in 2003-2004 to more than 38 percent in 2011-2012.
Overall, more than two-thirds of adults are either overweight or obese, and more than 6 percent are extremely obese.
There hasn't been a big impact on prevalence in the last eight years, but at least there's a leveling off, said obesity expert Dr. William Yancy, an associate professor of medicine at Duke University Medical Center in Durham, N.C.
"There are a bunch of competing factors that make it hard for people to manage their weight," Yancy said. "Genetics are involved, chemicals in foods and the environment may be involved. Clearly, the food environment stimulates us to eat more and more higher-calorie foods, and our environment also encourages us not to be active."
Those factors make it "really difficult" to maintain a healthy weight, he said. "I liken it to how difficult it is to get people to stop smoking," said Yancy. As with smoking, he said, it may take bigger policy changes to bring prevalence down, such as taxes and restrictions, but it's a complicated matter.
"People have to eat but they don't have to smoke, and there's a lot of controversy about what's a healthy food and what's not," Yancy said.
Ogden agreed there's no simple solution. "Obesity is obviously a multifactorial problem. It's very complex," he said, adding that surveillance of obesity in the United States will continue.