Having a normal overall BMI and a beer belly ("abdominal obesity") was found to be more dangerous than having a BMI in the obese range.

BrewBooks/Flickr PROBLEM: While the relationship between obesity and cardiovascular health is well understood, less is known about the risks associated with "central obesity," or excessive fat concentrated around the abdomen. A gut, if you will. Are those with fat primarily in this region at higher risk of death due to cardiovascular problems than those who are obese?

METHODOLOGY: A representative sample of 12,785 American adults was culled from the Third National Health and Nutrition Examination Study, which took place between 1988 and 1994, and matched to National Death Index. The subjects were grouped as normal, overweight, and obese based on their BMI, and then were further grouped as having a normal or high waist-to-hip ratio. In analyzing the risk of death, the researchers adjusted for age, gender, and race and for confounding factors like smoking, hypertension, and diabetes. The data was followed up this year. 

RESULTS: Of the 2,562 subjects who have passed away since this data was initially collected, 1,138 deaths were cardiovascular related. The risk of death for people of normal weight with central obesity was 2.08 times higher than for people with both a normal BMI and a normal waist-to-hip ratio. The risk of cardiovascular death, specifically, was 2.75 times higher for the former group. Both total and cardiovascular mortality were also higher in the group with normal BMI and a high waist-to-hip ratio than even in those with BMIs in the obesity range.

CONCLUSION: Having a pot belly, even if you have a normal body mass index, is associated with significantly increased -- even doubled -- mortality. It's even more dangerous than overall BMI.

IMPLICATIONS: These results suggest that paying attention to belly fat is even more important than monitoring one's overall body mass, and that a normal BMI does not necessarily equate with good cardiovascular health. Researchers discuss that this may relate to visceral adiposity -- fat within the abdomen, around the internal organs -- which is known to be particularly dangerous. Says Dr. Francisco Lopez-Jimenez, a cardiologist at the Mayo Clinic, "from a public health perspective, this is a significant finding."

The full study, "Normal-weight Central Obesity and Cardiovascular Mortality Risk in the U.S. Population," was presented at the European Society of Cardiology Congress.