Obesity Rate Will Reach at Least 42 Percent, Say Models of Social Contagion

And this is the best case scenario.

Researchers at Harvard University say America's obesity epidemic won't plateau until at least 42 percent of adults are obese, an estimate derived by applying mathematical modeling to 40 years of Framingham Heart Study data.

Their work, published this week in the journal PLoS Computational Biology, runs counter to recent assertions by some experts that the obesity rate, which has been at 34 percent for the past five years, may have peaked. An additional 34 percent of American adults are overweight but not obese, according to the federal government's Centers for Disease Control and Prevention.

The Harvard scientists say that their modeling shows that the proliferation of obesity among American adults in recent decades owes in large part to its accelerating spread via social networks.

"Our analysis suggests that while people have gotten better at gaining weight since 1971, they haven't gotten any better at losing weight," says lead author Alison L. Hill, a graduate student in Harvard's Program for Evolutionary Dynamics, Biophysics Program, and at the Harvard-MIT Division of Health Sciences and Technology. "Specifically, the rate of weight gain due to social transmission has grown quite rapidly."

The projections by Hill and colleagues are a best-case scenario, meaning that America's obesity rate could rise above 42 percent of adults. One silver lining is that their model suggests the U.S. population may not reach this level for another 40 years, making the future rate of increase much more gradual than over the past 40 years. Only 14 percent of Framingham Heart Study participants were obese in 1971.

"People. people who need people, are the heaviest people in the world." (apologies to Robert Merrill and Jule Styne)