Scientists at the University of Glasgow found that while smoking might be associated with lower overall weight it tends to push fat into central areas resulting in a bigger stomach – an unhealthy apple shape, rather than a healthy pear shape.
In their study, the researchers conducted a meta-analysis of 29 studies involving almost 150,000 participants containing data on their smoking habits, weight and waist circumference.
The analysis revealed a genetic variation in some smokers associated with an increase in the number of cigarettes consumed and a lower mean body mass index (BMI), thus adding evidence that heavier smoking leads to lower BMI.
But the data, published in the BMJ Open journal, also showed that while overall BMI in heavy smokers was lower, waist circumference was higher than non-smokers once BMI was accounted for.
Smokers who have the variant will consume an extra cigarette a day. The research suggests that for every copy of the genetic variant associated with increased cigarette consumption, waist circumference increased by 0.14% if BMI were to remain constant. The result suggests a preferential redistribution of fat towards the stomach.
Professor Naveed Sattar, of the Institute of Cardiovascular and Medical Sciences who co-led the study, said: “One barrier to smoking cessation is the fear of weight gain and whilst smoking lessens weight overall, it tends to push fat more into the central area so waist circumference is preferentially higher.
“So, when smoker 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.
“On the whole weight goes down in smokers. That’s true at point of smoking, but it means smoking is lessening the chance of putting fat on in the ‘safe bits’.
“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.”
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