WASHINGTON, Nov. 10 (UPI) -- Obesity is bad for health, however "skinny" people who carry extra weight around their mid-section may be at greater risk for early death than obese people, researchers found in a large study of adults in the United States.
Central obesity has been shown in previous studies to increase risk for cardiovascular disease and poses risks to health, however its potential effect on normal weight people has not been studied before, researchers said.
Measuring obesity and health risk simply by body mass index, or BMI, limits doctors' awareness of potential health risks because people with normal BMI may have central obesity and suffer some of the health effects of it.
"It's not just the fat you can see when your 'spare tire' rolls over your pant line," Dr. Daniel Neides, medical director of the Wellness Institute at Cleveland Clinic, told CBS News. "But it's actually the fat that is deposited within the abdomen and it really covers the organs within the abdominal cavity."
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Researchers in the study, published in the Annals of Internal Medicine, analyzed data on 15,184 adults between the ages of 18 and 90, and a little more than half of whom were women, collected as part of the National Health and Nutrition Examination Study.
They compared the relationship of obesity measured by BMI and waist-to-hip ratio with total and cardiovascular death risk, finding that men with normal BMI and a fat belly had an 87 percent higher risk of death than men with the same BMI and normal waist-to-hip ratio. In women, those with fat bellies and a normal BMI had a 48 percent greater death risk than those with normal BMI and normal belly fat.
"People with normal weight according to BMI can't be reassured that they don't have any fat-related health issues," Dr. Francisco Lopez-Jimenez, a professor of medicine at the Mayo Clinic and senior author of the paper, told the New York Times. "Having a normal weight is not enough. It's good only if the distribution of fat is healthy."
Although BMI has long been a reliable measure of health risk from excess fat, Dr. Paul Poirier, a researcher at the Institute of Cardiology at Laval University, wrote in an editorial published in Annals of Internal Medicine with the new study that measuring for central obesity is essential because doctors are missing a significant amount of life-threatening fat on the inside of people's bodies.
"Waist-to-hip ratio is a simple and reliable measure for central obesity, but it is infrequently used in daily clinical practice," Poirier wrote. "The long-term deleterious consequences of excess adiposity are marked and important. Although the utility of BMI has been borne out in epidemiologic studies, there are limitations to using BMI alone to assess adiposity in clinical practice. The numerator in the BMI calculation is total body weight and does not distinguish between lean and fat mass."
