February 03, 2008
Sunday

Is the health risk from obesity being exaggerated?

Most medical experts would say no. But a provocative minority says yes.

This week, two prominent skeptics match wits with two obesity experts in a heated debate in the British Medical Journal.

Patrick Basham, a lecturer at Johns Hopkins University, and John Luik are both health policy experts at the conservative Democracy Institute. They argue that there's a lot less to the obesity epidemic than meets the eye.

Robert Jeffery, a professor at the University of Minnesota, and Nancy Sherwood, a researcher at HealthPartners, say that the skeptics are simply denying the obvious.

Who says yes?

Pointing to increased life expectancy and reductions in heart disease in recent years, Patrick Basham and John Luik, coauthors of "Diet Nation: Exposing the Obesity Crusade," say scientists haven't proved obesity carries major health risks.

Opening shot:

"Media claims about an epidemic ... often exceed the scientific evidence and mistakenly suggest an unjustified degree of certainty."

What's normal?

Research in various countries "suggests that as populations grow healthier, prosperous, and long lived they gain in height and weight."

Shouldn't we be worried?'

The data are "highly equivocal in their support for claims of an epidemic." The average weight gain in the U.S. in the past 42 years has been about 20 pounds, or a half-pound a year. From 1999 to 2002, "there were no significant changes in the prevalence of overweight or obesity."

Isn't obesity deadly?

The evidence is not as strong as you might think. In 1997, the National Institutes of Health found that thin men had the same risk of dying prematurely as overweight men. Any increase in risk is relatively small compared to, say, smoking. "Despite the supposedly abnormal levels of overweight and obesity, life expectancy continues to increase," the two wrote in the British Medical Journal.

Doesn't obesity make us sicker?

There's reason for skepticism. The death rates from heart disease and stroke have been falling, not rising. There's no direct evidence that excess fat causes diabetes. "We argue ... that obesity is a symptom of Type 2 diabetes, rather than a cause," said Luik in an e-mail interview. "For instance, changes in physical activity and diet reduce diabetes risk even without loss of weight. How does this support a cause and effect relationship?"

Bottom line?

Health advocates have resorted to "deliberate exaggeration or, indeed, misrepresentation of the risks" of obesity.

Who says no?

Evidence of serious health problems caused or accelerated by obesity is overwhelming, say Robert Jeffery of the University of Minnesota and Nancy Sherwood of HealthPartners Research Foundation. They accuse Luik and Basham of cherry-picking data and ignoring the body of research.

Opening shot:

"The fact that obesity is developing rapidly in many parts of the globe is incontrovertible," they write in the British Medical Journal.

How much weight have we gained?

Obesity rates have tripled in the last two to three decades in many countries, including ours. Thirty years ago, 5 to 7 percent of U.S. kids were obese; by 2003-2004, it was 17 to 19 percent.

Why should we be worried?

"The adverse effects of obesity on health are well established," including high blood pressure, high cholesterol, diabetes, heart disease and some cancers. "We are facing the potential for a major health crisis." Some predict it will result in a decline in life expectancy in a few decades.

What's the biggest danger?

Diabetes. Weight gain is "strongly associated" with diabetes, which is rising dramatically. Yes, people can lower their risk without losing weight, says Sherwood, "but you'd still do much better if you lost weight."

Bottom line?

The skeptics cherry-pick their evidence, but the overall trend is clear. That's no exaggeration, said Sherwood. "What would be gained by that?"

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