Medical World Debates Risk of Being Pudgy
The 25 cutoff was chosen, he said, because of evidence that the risk of diabetes, high blood pressure and high cholesterol all seem to increase around that point.
The studies backing this up are mostly reviews of large population groups that look for ties between increasing weight and the risk of various diseases and death. The individual studies may have flaws, but taken together, many contend they draw a convincing picture of weight being on a continuum from good health to ill.
"Some say it's all made up, that there's no risk to being moderately overweight," says Dr. Lawrence J. Cheskin, director of the Johns Hopkins Weight Management Center. "But there is more and more data to show a very definite dose effect. The heavier you are, the greater your risk."
Some believe the ideal body weight is actually around a BMI of 20 or 21, or a willowy 115 pounds for that 5-foot-3 woman. Others put it closer to 24 or 25. "Everybody agrees that if your BMI is 28, you are at increased risk," says Dr. Steven Heymsfield of St. Luke's-Roosevelt.
This view is backed by studies showing mortality inching up gradually when BMIs reach the high 20s, then climbing more sharply through the 30s and beyond.
One of the most recent, published last year in the Journal of the American Medical Association, concludes that white men and women lose about an average year of life if their BMIs top 26 or 27 by the time they reach middle age. However, for reasons that are not easy to explain, this may not be true for blacks. They actually seem to live a year or so longer if overweight but not obese.
While some question the scientific rigor of the mortality estimates, there is less disagreement that common health problems increase among people who are overweight but still below the obesity threshold of a BMI of 30.
For instance, a woman with a BMI of 26 is twice as likely as one who is 21 to develop coronary heart disease. She is twice as likely to get high blood pressure. And she is eight times as likely to get diabetes. Of course, a very thin woman has only a tiny risk of these diseases, so a risk that is double or triple may still be small.
Nevertheless, national health surveys show that about a quarter of people who are overweight but not obese have metabolic syndrome, a particularly worrisome combination of high blood sugar, high blood pressure, low HDL and high triglycerides.
Diabetes is an especially important concern, even for those nowhere near rotund. In fact, the ideal size for avoiding this disease appears to be around a BMI of 22. The risk goes up 25 percent with each unit of BMI after that, and it appears to be especially great for those with pot bellies, even small ones.
Of course, just because surveys of thousands of people show a clear link between rising BMIs and bad health doesn't mean that any particular individual is in trouble with a BMI that hits 25. Many lucky people carry their extra pounds with no ill effect, especially if they have normal blood sugar, healthy blood pressure and no worrisome cholesterol signs.
Many experts contend the biggest hazard of being overweight is what almost inevitably comes next.
"Fat people get fatter," says Dr. Peter McCullough, head of the weight control center at Beaumont Hospital in suburban Detroit. "It is very clear that those who are overweight will become obese over time. People need to understand they have to get this under control."
EDITOR'S NOTE: Medical Editor Daniel Q. Haney is a special correspondent for The Associated Press.
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