Beware the cigarette belly.

All other things being equal, smokers usually weigh less than nonsmokers. But not all smokers are slim. And a new study now indicates that when smokers start putting on fat, they are slightly more likely than nonsmokers to deposit it around the belly. Because people who tend to plump out around the waist rather than the hips are more likely to develop heart disease, this finding may offer one partial explanation for smokers' higher risk of this disease, the study's authors speculate.

The researchers correlated smoking habits, diet, alcohol consumption, exercise and body build in 765 Boston-area men, aged 43 to 85, who have participated in a "normative aging study" undertaken by the Department of Veterans Affairs in 1961. Smokers in the study weighed less than nonsmokers and had a smaller body-mass index (the weight-to-height-squared ratio used in determining obesity). However, smokers also had a higher abdomen-to-hip ratio than former- or never-smokers--a trend independent of age, alcohol use, exercise and body mass.

"The mechanism by which smoking increases [abdominal] accumulation of body fat is unknown," Scott T. Weiss of Brigham and Women's Hospital in Boston and his co-workers write in the May AMERICAN JOURNAL OF CLINICAL NUTRITION. The researchers found smokers more likely to dine on foods high in saturated fat, but their statistical analyses indicate that while this dietary fat correlated with body-mass index, it did not affect the abdomen-to-hip ratio.