The more your belly sticks out, the greater your risk of developing heart disease, a new study shows.

“The message is really obesity in the abdomen matters even more than obesity overall,” Dr. Carlos Iribarren of Kaiser Permanente of Northern California in Oakland, the study’s lead author, told Reuters Health.

Body mass index (BMI), a gauge of weight in relation to height, is a fairly crude way to judge a person’s heart disease risk based on obesity, he noted. For example, muscular people may have a high BMI and be perfectly healthy.

In the current study, Iribarren and his team tested whether sagittal abdominal diameter, or SAD, which is the distance from the back to the upper abdomen midway between the top of the pelvis and the bottom of the ribs, would improve the accuracy of BMI in predicting heart disease risk.

Waist circumference is widely used to measure obesity in the abdominal area, Iribarren noted. But while there are many ways to measure a person’s waist, he added, SAD, which is evaluated by a doctor or nurse with a caliper, is much more standardized, and therefore probably less subject to error.

He and his colleagues looked at 101,765 men and women who underwent checkups between 1965 and 1970, which included SAD measurements, and were then followed for about 12 years.

Men with the largest SAD were 42 percent more likely to develop heart disease during follow-up compared to those with the smallest SAD, while a large SAD increased heart disease risk by 44 percent for women, Iribarren and his team found.

Within BMI categories, the researchers found, heart disease risk rose with SAD; even among men of normal weight, heart disease risk was higher for those with bigger bellies.

The relationship between SAD and heart disease risk was strongest among the youngest men and women, which is not surprising, Iribarren said, given that people who develop central obesity younger in life would likely have more serious problems.

“I think it has important implications for prevention,” he said. ” Don’t let this happen to you when you’re young, that’s kind of the message.”

SOURCE: American Journal of Epidemiology, December 15, 2006