Obesity May Stall Trend of Increasing Longevity
Thursday, March 17, 2005
Obesity has started to erode the gains Americans have made in extending their life spans and will stall the long trend toward increasing longevity unless the nation takes aggressive steps to slim down, researchers said yesterday.
Illnesses caused by obesity are already shortening the average U.S. life by at least four to nine months -- greater than the impact of car accidents, homicides and suicides combined -- a first-of-its-kind analysis has determined.
Within 50 years, if the trend is not reversed, obesity will cut the average life span by at least two to five years, which would exceed the effects of all cancers, the researchers estimated. That could overtake all gains from healthier lifestyles and medical advances and cause longevity to plateau or perhaps decline, they projected.
Except for major catastrophes such as famines, wars and pandemics, the life span of the average American has been increasing steadily for the past two centuries, reaching an all-time high of 77.6 years in 2003, the most recent data show.
"The take-home message is that obesity clearly needs to be considered in an entirely new light -- it is far more dangerous than we ever thought," said S. Jay Olshansky, a University of Illinois demographer who led the study in today's New England Journal of Medicine.
Several other researchers agreed, saying the finding that obesity is actually undermining longevity should be a wake-up call.
"These results are stunning and reinforce the enormous toll that obesity is taking on the health and happiness of the population," said Kelly D. Brownell, who directs the Center on Food Policy and Obesity at Yale University.
Other researchers, however, said the underlying assumptions were excessively pessimistic. The study assumed, for example, that everyone who is overweight will suffer health problems.
"I don't think this is based on solid, scientific ground," said Glenn A. Gaesser, a professor of physiology at the University of Virginia in Charlottesville who frequently questions the impact of obesity. "It's nonsensical, really."
But the researchers said their estimates were conservative in several ways, including the fact that they focused exclusively on adults. The true impact is likely to be much greater as obese children age and begin suffering elevated rates of diabetes, heart disease and cancer, they said.
"It's sort of like a massive tsunami heading towards the shoreline," said David S. Ludwig, an obesity expert at the Harvard Medical School and Children's Hospital in Boston who worked with Olshansky. "It's going to peak in a massive public health crisis."
At least two-thirds of Americans are now overweight, including about one-third who are obese.
Obesity significantly increases the risk of a host of serious health problems, including cancer, heart disease and diabetes.
The researchers calculated how much longer Americans would be living if obesity did not exist, using data from a large federal assessment of obesity rates and estimates of the health impact of obesity by the University of Alabama at Birmingham School of Public Health and the National Center for Health Statistics.
If obesity were magically eliminated, the overall life span would be at least one-third to three-quarters of a year longer, they found. Minorities would be most affected because they are more prone to obesity and tend to get lower-quality health care, the researchers found.
"Unless we do something, today's younger generation will for the first time in the modern era experience shorter and less healthy lives than their parents," Olshansky said.
Ironically, that could ease the pressure on the Social Security system, the researchers said.
"The U.S. population may be inadvertently saving Social Security by becoming more obese," they wrote, "but the price to be paid by obese people themselves and the economy is already high enough to justify considerably increased spending on public health interventions aimed at reducing the incidence and severity of obesity."
In an accompanying editorial, demographer Samuel H. Preston of the University of Pennsylvania said that although some of the study's assumptions may be "excessively gloomy," he agreed that the "rising prevalence and severity of obesity are capable of offsetting the array of positive influences on longevity."