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Study Cites Obesity As Longevity Threat

Posted on: Thursday, 17 March 2005, 15:00 CST

Mar. 17--Obesity has become such a pervasive health threat that by the middle of this century it could reverse the long, steady rise in US life expectancy, a team of scientists report in a provocative study published today.

The epidemic of obesity among children will lead to a surge of heart disease, strokes, diabetes, and cancer -- illnesses that can drastically shorten lifespans -- and will eventually begin to offset the longevity gains from medical advances, the authors write in today's New England Journal of Medicine.

Their predictions are controversial, and an editorial in the same issue calls the study "excessively gloomy."

But the new study could have implications for the Social Security debate. The authors say the future burden on Social Security will not be as great as President Bush and others have warned, because seniors will not live as long as the government has predicted. Obesity-related complications would instead swell spending on government health programs.

Increasing life expectancy was among the greatest triumphs of the 20th century, as advances ranging from vaccines to antibiotics to improved sanitation added three decades or more to the average lifespan in many developed nations. Wars and plagues have historically caused downturns in national life expectancy, and the study's authors portrayed widespread obesity as similarly cataclysmic.

"It can be compared to a massive tsunami heading toward the US," said Dr. David Ludwig, an obesity specialist at Children's Hospital Boston and an author of the study. "If you wait until you can see the ocean headed toward the shore, it's too late to take action."

Already, obesity is reducing US life expectancy by up to nine months, the study found. Though seemingly trivial, the figure means that obesity currently lowers life expectancy more than homicide, suicide, and fatal accidents combined, though other trends continue to push up the overall figure.

But later in the century, as millions of overweight children age, obesity could depress US life expectancy by two to five years, which could overwhelm positive trends and result in a net drop in life expectancy, the study predicted.

Some demography specialists said the study was overly pessimistic, arguing that new medical treatments, dropping smoking rates, and increasing education levels would continue to nudge US life expectancy upward for the rest of the century. Richard Suzman, associate director for behavioral and social research at the National Institute on Aging, called the study's conclusions "plausible but unlikely."

"I think obesity is just one of a large number of other factors, and that probably, though not necessarily, they will counterbalance increasing obesity," said Suzman, whose agency has funded work projecting life expectancy.

The study's authors said the longevity downturn they describe is not inevitable.

Ludwig said it would take "fundamental change" to reduce obesity, including overhauls of school lunch and physical education policies, tight regulations on food advertising, widespread nutrition education, and increased spending on obesity treatments.

"Unfortunately, we lack anything resembling a national strategy on childhood obesity," Ludwig said.

Life expectancy is the average number of years a newborn can be expected to live. Last month, federal health officials announced that US life expectancy in 2003 was 77.6 years. In 1900, it was 47.3. Life expectancy has edged up in recent years, as death rates from cancer and heart disease have declined. But the new study predicts this trend will end.

"We think life expectancy will continue to rise for roughly the next five to 10 years, but after that, when obese children start reaching their 20s and 30s, obesity-induced mortality will start taking effect," said Dr. S. Jay Olshansky, a public health professor at the University of Illinois at Chicago and the lead author of the study. He said life expectancy would stagnate for some time and then begin to decline near the middle of the century, though he said it was difficult to estimate precisely when that would happen.

Rapidly increasing obesity rates, particularly among children, are the driving force behind the prediction. Obesity has nearly tripled among US children over the last three decades, according to federal statistics. In 2000, more than 15 percent of children age 6 to 19 were obese. Even the youngest are affected: 10 percent of children ages 2 to 5 were obese, double the rate three decades earlier. Among US adults, obesity prevalence increased by about 50 percent per decade between 1980 and 2000. Two-thirds of US adults are now overweight or obese.

Obese people face elevated risks for heart disease, diabetes, cancer, and other ailments. A previous study estimated that obesity reduces lifespan by between five and 20 years. The researchers took this and other data on obesity risks and combined it with demographic data to calculate that US life expectancy would have been four to nine months longer in 2000, if obesity had been eliminated.

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Source: The Boston Globe

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