Obesity May Cut U.S. Life Spans, Study Says

Mar. 17–The growing epidemic of obesity could cause the first drop in Americans’ life expectancy in modern times, according to a new study that suggests weight problems could cancel out life-extending benefits from medical advances in the coming decades.

Today’s children, who are becoming obese at unprecedented rates, will suffer the greatest loss of longevity, according to the report. A national team of experts on aging and obesity compiled the estimates, led by S. Jay Olshansky, a biological demographer at the University of Illinois at Chicago.

Obesity already is taking away up to nine months of life, on average, from life expectancies in the U.S., the study found. That figure could reach five years or more if America cannot reverse the trend of rising obesity rates.

“We don’t realize the situation we’re putting ourselves in by pushing our children to higher and higher weights,” said Olshansky, whose study was published in Thursday’s issue of the New England Journal of Medicine. “They will carry the effects of this with them throughout their lives.”

A drop in life expectancy would bring a halt to centuries of steady gains in longevity and potentially shift debates over programs like Social Security. Government projections for the program assume that Americans will continue to live longer and draw more money from the system. Life expectancy in 2003 was 77.6 years–up from 77.3 in 2002, according to the federal Centers for Disease Control and Prevention.

But if average life expectancy stagnates, that would reduce the amount of money needed to keep entitlement programs afloat.

“It’s not the way you want to fix Social Security,” Olshansky said.

Other researchers welcomed the study as the first credible projection of obesity’s long-term damage to society. But some doubt the losses caused by obesity will outpace expected longevity gains from new treatments and other advances.

“I expect life expectancy to keep chugging upwards as it has been,” said Ronald Lee, a professor in the department of demography at the University of California at Berkeley. While the new work underlines that obesity is a serious threat, crises such as tuberculosis and AIDS have not slowed the broader improvement in longevity, Lee said.

Obesity is unique in its huge and skyrocketing impact on the young, the report’s authors believe. Weight problems have more than quadrupled for some groups of young people since the 1970s.

Lolita Daniels of Bolingbrook said she’s struggled to cut junk food and schedule more exercise for her 8-year-old son, Nicholas, who weighs 115 pounds. His weight can aggravate his asthma and puts him at risk for more serious health problems. But Nicholas has only put on more pounds in the last year, even since he started going to the obesity clinic at Children’s Memorial Hospital in Chicago.

“He wants to lose weight, he does,” Daniels said. “He’s been trying for so long, sometimes I think he doesn’t believe he can.”

Any forecast of how long people will live decades from now carries deep uncertainty. The study’s leaders said although their work previews only one possible future, it makes use of vital information lacking in other projections that have ignored the effect of obesity.

The new report is based on past studies of death rates, which have shown that people who are obese or overweight have their lives cut short by five to 20 years. Obesity can speed death by contributing to heart disease, diabetes, stroke and many other conditions. People who became obese as children tend to have especially early deaths.

Olshansky and his colleagues plugged that data about obesity’s effects on individuals into an estimate of how obesity is pulling down life expectancy for the U.S. as a whole. They calculated that if the problems of overweight and obesity were to vanish tomorrow, that would increase overall U.S. life expectancy by four to nine months.

That may not sound like a lot, but it’s greater than the effect on life expectancy of all accidents, murder and suicide, experts said. Even if researchers were to cure all forms of cancer, that would increase overall life expectancy by just three years–less than the potential negative effect of obesity in the future.

One of the report’s co-authors, Dr. David Ludwig of Children’s Hospital in Boston, compared the obesity projections to seeing the crest of a tsunami headed for shore.

Ludwig said the U.S. is especially vulnerable, because it lacks an effective national strategy for dealing with obesity. He cited the fact that federal regulators have no power to limit marketing of fattening food to children, even though studies suggest that kids who see ads for junk food are more likely to eat those items and less likely to eat fruits and vegetables.

“Why aren’t we seeing policies to protect children?” Ludwig said.

Fears about childhood obesity weren’t the original impetus for the new study, Olshansky said. Rather, it stemmed from an older debate about whether American life expectancies will inevitably continue their historic climb.

Two years ago, the trustees of the Social Security program held a meeting with Olshansky, Lee and another Berkeley demographer, John Wilmoth, to ask for their recommendations about how the program should estimate life expectancy. Olshansky and Lee said they gave opposing advice: Olshansky urged the trustees to consider scaling back their longevity projections, while Lee and Wilmoth thought the program should increase its estimates to reflect their view that the gains of the past will continue. The trustees took Lee and Wilmoth’s advice and hiked their projections slightly.

Olshansky and other experts had long believed such estimates were overly optimistic. They argued that past gains in longevity stemmed largely from reductions of deaths in infancy and childhood–advances that society is unlikely to match in the future.

But Olshansky wondered if the problem went deeper. Might ailments like obesity not just slow the rate of increase in life expectancy, but actually start to reverse the trend?

“Forecasting this by looking at past trends is like forecasting the weather by looking at previous patterns in the area, rather than what’s on the horizon,” Olshansky said.

Lee said life expectancy rose in the past because of health improvements like better childhood nutrition. Even now that childhood obesity is the bigger worry, the gains have stayed remarkably consistent. Life expectancy has increased in developed nations by an average of three months per year since the mid-1800s, slowed only briefly by catastrophes like the 1918 flu pandemic.

But obesity could be the first lasting setback, Olshansky said.

“We always assume that things will be better–we’ll live longer and be healthier,” Olshansky said. “Right now the evidence doesn’t support that.”

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