Normal-weight people with fat bellies have a higher risk of death than the obese, according to data presented at the European Society of Cardiology conference in Munich.
People with a normal body mass index, or BMI, and "central obesity" as defined by a high waist-to-hip ratio had the greatest risk of cardiovascular-related death and the highest death risk overall, researchers said in a statement. The risk of cardiovascular death was 2.75 times higher and the risk of death from all causes was 2.08 times higher compared with subjects with normal BMI and a normal waist-to-hip ratio.
"We knew from previous research that central obesity is bad, but what is new in this research is that the distribution of the fat is very important, even in people with a normal weight," Francisco Lopez-Jimenez, senior author of the study and a cardiologist at the Mayo Clinic in Rochester, Minn., said in the statement. "This group has the highest death rate, even higher than those who are considered obese based on BMI."
The risk of death may be related to a higher visceral fat accumulation, which is associated with insulin resistance and other risk factors, said Karine Sahakyan, a research fellow at the Mayo Clinic. Risk for fat-bellied subjects may also be connected to a limited amount of "protective" fat on the hips and legs and a relatively limited amount of muscle mass, she said.
The study included 12,785 people representative of the U.S. population with an average age of 44 years where 47.4 percent were male. Over a median of about 14 years there were 2,562 deaths, of which 1,138 were cardiovascular-related, the study said.
BMI, which is calculated using a person's height and weight, is considered normal if it's between 18.5 and 24.9, according to the U.S. National Institutes of Health. A normal waist-to-hip ratio is less than 0.85 for women and less than 0.9 for men, Sahakyan said. The causes of central fat distribution have yet to be determined, she said.
Given that only one-third of the U.S. population is normal weight, it's unlikely that today's findings apply to a large portion of the population, said Donna Arnett, the president of the American Heart Association.
People should know their waist measurement, and those who are prone to have central fat distribution should talk to a physician about their diet and managing their cholesterol, blood pressure and blood-sugar levels, Arnett said.