The decision to give up smoking seems easy enough in the mind of your average non-smoker. However, smokers can always come up with one or two reasons for why they can’t give up nicotine just yet. One of the most common reasons smokers give for not kicking the habit is potential weight gain. A recent study published in International Journal of Epidemiology has revealed a potential link between consuming large amounts of tobacco and lower body weight.

"We found a clear disagreement between observational and genetic analyses," lead researcher Professor Børge Nordestgaard said in a statement. "Observational analyses suggested higher body weight, BMI, waist circumference, and hip circumference for higher tobacco consumption in current smokers, while genetic causal analysis pointed in the opposite direction. These differences are most likely caused by residual confounders not included in the observational regression models."

Nordestgaard and his colleagues used the Copenhagen General Population Study to gather data on 80,342 participants, including 15,220 current smokers. Researchers from Herlev Hospital and Copenhagen University Hospital also used a polymorphism in proximity to the cholinergic receptor, nicotinic, alpha 3 (CHRNA3) gene as a genetic proxy for high tobacco consumption among smokers.

Separate analyses showed an association between the CHRNA3 genotype and body weight among current smokers, but not former smokers or never-smokers. Observational analyses revealed a body weight increase of 1.1 pounds per 10 cigarettes smoked each day. However, genetic analyses showed that doubled carriers of the high smoking genotype had, on average, a 2.64-pound lower body weight.

"Reverse causality may also be a factor, where having a higher body weight in itself could lead to someone taking up smoking, or increasing their tobacco consumption," the researchers said. "Smoking and obesity remain two leading modifiable risk factors for death. Which of them is associated with the greater health risk has not been subject to much investigation, and despite our findings, we do not recommend the decision to start or continue smoking in order to control body weight."

According to the Centers for Disease Control and Prevention, withdrawal symptoms, stress, and weight gain are the most common reasons smokers give for not quitting or starting again. Similar to caffeine, tobacco is an appetite suppressant that research shows can also increase your metabolism. After quitting, a smoker’s appetite and metabolism returns to normal, meaning he can consume more and burn fewer calories.

On the other hand, a smoker who doesn’t quit increases his risk for lung cancer, heart disease, stroke, and a bevy of other life-threatening conditions. One thing's for certain: The benefits of kicking a nicotine habit outweigh the side effects.

Source: Winsløw U, Rode L, Nordestgaard B. High tobacco consumption lowers body weight: A Mendelian randomisation study of the Copenhagen General Population Study. International Journal of Epidemiology. 2015.