Unlike a previously-believed thought that weight gain leads to a protruded stomach, a latest study has associated heavy smoking with the appearance of a fat stomach. According to the researchers at the University of Glasgow, heavy smokers are more likely to develop pot bellies as smoking pushes the accumulated fat in the body to the central area around the stomach.

While people fear that if they give up smoking, they will end up gaining weight, the researchers said that smokers now have a reason to give up smoking they are at a greater risk of developing stomach fat and apple-shaped bellies.

As part of the study, the researchers looked at the data from 29 previously conducted studies. The studies spanned across a sample population of 150,000 people, and noted their certain characteristics, including smoking habits, waist circumference and body weight.

The researchers discovered that in some smokers, the greater the number of cigarettes he or she consumed, the lower was his or her body mass index (BMI) due to a genetic variation. The findings suggested that heavier smoking leads to a decrease in the BMI.

However, the researchers found that even though the BMI decreased, the circumference around the waist of the smoker was greater than that of a non-smoker. When the BMI of the subject remained constant, the waist circumference increased by 0.14 percent, the researchers reported.

The co-author of the study, Professor Naveed Sattar of the Institute of Cardiovascular and Medical Sciences said that even though smoking lessens the overall body weight, it does push the fat into the central area so that the overall circumference of the waist is increased. The complete details of the study have been published in the BMJ Open Journal.

"So, when smokers put on weight, they will show bigger tummies for same weight gain than non-smokers and this may also be linked to their greater risk for diabetes,” said Sattar, in a statement. “If confirmed, a tendency for smokers to acquire an ‘apple shape’ due to increasing central adiposity might provide a novel health promotion message to encourage smoking cessation.”