People who are normal weight but have fat concentrated in their bellies have a higher death risk than those who are obese, according to research from the Mayo Clinic.
Those studied who had a normal body-mass index but also had central obesity -- meaning a high waist-to-hip ratio -- had the highest cardiovascular death risk and the highest death risk from all causes, the analysis found.
"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," said Mayo cardiologist Dr. Francisco Lopez-Jimenez, senior author of the study.
Findings of the study were presented Monday at a cardiology conference in Munich.
"This group has the highest death rate, even higher than those who are considered obese based on body mass index," Lopez-Jimenez said. "From a public health perspective, this is a significant finding."
The study included 12,785 adults 18 and older from the CDC's Third National Health and Nutrition Examination Survey, which is a representative sample of the U.S. population. Data was matched with the National Death Index to assess deaths at follow-up.
Those studied were divided by body mass index into three categories (normal: 18.5-24.9 kg/m2; overweight: 25.0-29.9 kg/m2; and obese: >30 kg/m2) and two categories of waist-to-hip ratio (normal: <0.85 in women and <0.90 in men; and high: e0.85 in women and e0.90 in men).
Many people know their body mass index these days, but it's also important for them to know that a normal one doesn't mean their heart disease risk is low, adds Dr. Lopez-Jimenez.
Where your fat is distributed on your body can mean a lot. In fact, belly fat is different than other fats because verserial fat goes under the muscles and can't be squeezed.
This research was funded in part by National Institutes of Health.