ESC 2012 Report – Normal weight and belly fat spells higher risk of CVD than obesity only

by Bruce Sylvester – Normal weight persons with weight concentrated in their belly run a higher death risk of CVD-related death than obese-only individuals, researchers reported at ESC.

“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 lead author  Francisco Lopez-Jimenez, MD, cardiologist at the Mayo Clinic in Rochester, Minnesota. “This group has the highest death rate, even higher than those who are considered obese based on BMI. From a public health perspective, this is a significant finding.”

The investigators analyzed data from 12,785 subjects aged 18 years and older from the Third National (USA)Health and Nutrition Examination Survey (NHANES III) Body measurements such as height, weight, waist circumference and hip circumference were included in the analysis, as well as socioeconomic status, comorbidities, physiological and laboratory measurements.

The investigators matched baseline data to the National Death Index, in order to evaluate incidence of  death at follow up.

They divided the subjects into three categories of BMI (normal: 18.5-24.9kg/m2; overweight: 25.0-29.9kg/m2; and obese: >30kg/m2) and two categories of waist-to-hip ratio (normal: <0.85 in women and <0.90 in men; high: ≥0.85 in women and ≥0.90 in men).

They adjusted the analyses for age, sex, race, smoking, hypertension, diabetes, dyslipidemia and baseline BMI. They excluded subjects with chronic obstructive pulmonary disease and cancer.

Mean age of subjects was 44 years and 47.4% were men. Median follow up period was 14.3 years.

There were 2,562 deaths, and 1,138 were cardiovascular related.

Subjects with normal BMI but central obesity (high waist-to-hip ratio) had the highest cardiovascular death risk and the highest death risk from all causes. The risk of cardiovascular death was 2.75 times higher and the risk of death from all causes was 2.08 times higher in normal weight obese subjects compared to subjects with normal BMI and normal waist-to-hip ratio.

“To our knowledge it is the first study that evaluated nationwide estimates of death in central obesity even in the absence of obesity as measured by BMI,” said investigator Karine Sahakyan, MD,  cardiology research fellow at the Mayo Clinic in Rochester, Minnesota. “The high risk of death may be related to a higher visceral fat accumulation in this group, which is associated with insulin resistance and other risk factors, the limited amount of fat located on the hips and legs, which is fat with presumed protective effects and to the relatively limited amount of muscle mass.”

“Many people today know their BMI,” added  Lopez-Jimenez. “Our research shows that if a person has a normal BMI, this by itself should not reassure them that their risk for heart disease is low. Where their fat is distributed on their body can mean a lot, and that can be determined easily by getting a waist-to-hip measurement, even if their body weight is within normal limits.”