If your paunch is fatter than your haunch, the chances are you're at greater risk of having a heart attack, a stroke or diabetes.

Scientists at a recent American Heart Association meeting said that a series of studies in the United States, Europe and Canada have now confirmed that a pooling of fat about the middle is a clear signal of heart attack risk.A Santa Claus-style belly may be cute, but it can be as dangerous to the heart as cigarette smoking, high blood pressure or excess cholesterol in the bloodstream, said Per Bjorntorp of the University of Goteborg in Sweden.

"If a person has normal weight, but the fat is distributed wrong, it could be a risk," said Bjorntorp. "When you compare it to the other risk factors, it is about the same strength."

He said he studied a group of 900 men and 1,400 women and found that those who had more fat on the waist than on the buttocks tended to have a greater number of heart attacks. Those with belly blubber also experienced more strokes and were more apt to develop diabetes.

Bjorntorp said the study showed that men whose waists measured the same or more than their hips were more apt to have a heart attack than those who carried their weight elsewhere. For women, he said, the risks increase when the waist size was 80 percent of the hip size. And the fatter the waist, the higher the risk, he said.

In effect, if you're shaped like a barrel, you've got a greater chance of having a heart attack than if you're shaped like a pear.

A Canadian study of identical twins showed that the rate of weight gain and the distribution of fat may be determined, in part, by genetics.

Claude Bouchard of Laval University in Ste-Foy, Quebec, Canada, said he picked 12 pairs of identical twin males, aged 19 to 27, and overfed them by 1,000 calories a day during a 100-day stay in a dormitory.

At the end of the study, all of the twins gained from eight to 26 pounds. The brothers all tended to gain about the same, but there was an almost fivefold difference between sets of twins who were "high gainers" and "low gainers", indicating a genetic difference, said Bouchard.

Also, he said, the brothers all tended to follow the same pattern of weight distribution, but some sets of twins gained the additional fat in the waist while others gained it in the hips.

Another study, using monkeys, showed a result similar to the Swedish study.

Carol Shively of the Bowman Gray School of Medicine in Winston-Salem, N.C., said that in a laboratory colony of monkeys, the females that tended to distribute fat to their abdominal area were three times more likely to develop clogged coronary arteries than those who distributed bodily fat differently. Blocked arteries is a primary cause of heart attack.

She said the fat-waisted monkeys also experienced poor ovulation and tended to develop high levels of circulating cortisone, a hormone typically secreted during stress.

C. Wayne Callaway, a member of the AHA nutrition committee, said scientists are not certain why waist fat tends to lead to heart attack, but some studies have shown that the fat cells stored in the abdomen are different from fat cells stored elsewhere.

"The abdominal fat is more easily mobilized (metabolized by the body)," he said. "This may tend to raise the lipid level (cholesterol is a lipid) in the blood stream."