Having a large amount of such "visceral fat" is associated with increased risk of heart disease, high blood pressure and diabetes, said Dr. Kerry Stewart, an associate professor of medicine at Johns Hopkins University in Baltimore, Maryland.

It's not clear if switching to a diet containing more unsaturated fats, like those found in vegetable oils, will reduce or prevent the accumulation of visceral fat, Stewart said.

However, there are many reasons to eat diets low in saturated fats, including lowering one's risk of heart disease and high cholesterol, according to Stewart.

"Our study would suggest that less visceral fat is another reason," Stewart said.

The research was scheduled to be presented Sunday in Chicago at the American College of Cardiology's annual meeting.

In the study, Stewart and colleagues asked 84 people between 55 and 75 years of age to record their diet over a three-day period. The participants were nonsmokers who did not have heart disease or diabetes and lived a sedentary lifestyle.

The researchers then performed abdominal scans to measure the amount of visceral fat, and measured the patients' waist circumference relative to their hip size.

The bigger the waistline in relationship to hip size -- those with potbellies, in other words -- were more likely to have high amounts of visceral fat padding organs.

And a diet higher in saturated fats with respect to unsaturated fats was associated with more visceral fat.

Visceral fat, unlike fat that accumulates just under the skin, is not visible. According to Stewart, men tend to have more visceral fat than women, even though they might have the same amount of fat in the abdomen. This might partly explain why men develop heart disease at a younger age then women, Stewart said.

This study is part of a larger one that is examining the effect of exercise on the heart health of middle-aged and older people and will also assess the effects of exercise on visceral fat levels.

Joel Mosley is a graduate of The Masters College with a degree in bio-mechanics and has been a professional trainer in the fitness industry for the past 11 years. He has been a certified personal trainer for 9 years, with one year as the #1 trainer at Gold