Obesity will fuel drop in U.S. life span, study says

CHICAGO — U.S. life expectancy will fall dramatically in coming years because of obesity, a startling shift in a long-running trend toward longer lives, researchers contend in a report published Thursday.

By their calculations — disputed by skeptics as shaky and overly dire — within 50 years obesity likely will shorten the average life span of 77.6 years by at least two to five years. That's more than the impact of cancer or heart disease, said lead author S. Jay Olshansky, a longevity researcher at the University of Illinois at Chicago.

This would reverse the mostly steady increase in American life expectancy that has occurred in the past two centuries and would have tremendous social and economic consequences that could even inadvertently help "save" Social Security, Olshansky and colleagues contend.

"We think today's younger generation will have shorter and less healthy lives than their parents for the first time in modern history unless we intervene," Olshansky said.

Already, the alarming rise in childhood obesity is fueling a new trend that has shaved four to nine months off the average U.S. life span, the researchers say.

With obesity affecting at least 15 percent of U.S. school-age children, "it's not pie in the sky," Olshansky said. "The children who are extremely obese are already here."

The report appears in the New England Journal of Medicine. In an accompanying editorial, University of Pennsylvania demography expert Samuel H. Preston calls the projections "excessively gloomy."

Opposing forecasts, projecting a continued increase in U.S. longevity, assume that obesity will continue to worsen but also account for medical advances, Preston said.

Still, failure to curb obesity "could impede the improvements in longevity that are otherwise in store," he said. Americans' current life expectancy already trails more than 20 other developed countries.

Dr. David Ludwig of Children's Hospital Boston, a study co-author, cited sobering obesity statistics:

• Two-thirds of U.S. adults are overweight or obese; one-third of adults qualify as obese.

• Up to 30 percent of U.S. children are overweight, and childhood obesity has more than doubled in the past 25 years.

• Childhood diabetes has increased 10-fold in the past 20 years.