Study says obesity dangers overstated.

Byline: Rob Stein The Washington Post

WASHINGTON - Being overweight boosts the risk of dying from diabetes and kidney disease but not cancer or heart disease, and carrying some extra pounds appears actually to protect against a host of other causes of death, federal researchers reported Tuesday.

The counter-intuitive findings, based on a detailed analysis of decades of government data about more than 39,000 Americans, suggest that being overweight does carry risks, but the dangers may be less dire than experts thought.

"The take-home message is that the relationship between fat and mortality is more complicated than we tend to think," said Katherine Flegal, a research scientist at the Centers for Disease Control and Prevention in Atlanta, who led the study. "It's not a cookie-cutter, one-size-fits-all situation where excess weight just increases your mortality risk for any and all causes of death."

The study, published in the Journal of the American Medical Association, was greeted with mixed reactions. Some praised it for providing persuasive evidence that the dangers of fat have been overblown.

"What this tells us is the hazards have been very much exaggerated," said Steven Blair, a professor of exercise science, epidemiology and biostatistics at the University of South Carolina. "It's just not as big a problem as people have said."

But others dismissed the findings as fundamentally flawed, saying an overwhelming body of evidence has documented the risks of being either overweight or obese.

"It's just rubbish," said Walter Willett, professor of epidemiology and nutrition at the Harvard School of Public Health. "It's just ludicrous to say there is no increased risk of mortality from being overweight. ... From a health standpoint, it's definitely undesirable to be overweight."

The proportion of flabby Americans has been rising steadily, and two-thirds are now classified as overweight, including about one-third who have put on so many pounds they qualify as obese. The trend has triggered widespread warnings of an impending epidemic of diabetes, heart disease, cancer and other ailments.

Flegal and her colleagues raised the possibility two years ago that being overweight was less risky than feared. Their analysis of data from decades of federal surveys concluded that people who were overweight - but not obese - had lower overall mortality rates than those of normal weight. But their study came under heavy criticism.

In the new research, the team sought to confirm and expand on the original findings, examining additional data from later surveys and parsing individual causes of death across a range of weights. The analysis is based on the best health statistics federal scientists collected between 1971 and 2004, including cause-of-death data from 2.3 million adults from 2004. The researchers used federal definitions of "overweight" and "obesity" based on body mass index.