Heavy smokers, smokers who are obese gain more weight after quitting

Quitting smoking may lead to some weight gain but how much weight gain depends on the individual. Previous research shows that for some it can be just a few pounds, but for others it can be more than 25 pounds. Unfortunately, factors that can help predict the amount of weight a smoker may gain are not well understood.

"Many smokers are concerned about gaining weight after quitting smoking and this can be a barrier for them when they are considering whether or not to make a quit attempt," said Susan Veldheer, a registered dietitian in the Department of Public Health Sciences, Penn State College of Medicine. "Being able to easily identify smokers who may gain more weight when they quit is important so that we can work with patients to tailor their treatment plan."

To better understand personal factors that may contribute to weight gain, the researchers analyzed data from 12,204 participants in the National Health and Nutrition Examination Survey. They looked at the number of cigarettes smoked per day and body mass index before quitting, to see how these factors may have affected weight change over 10 years. Findings were reported in International Journal of Obesity.

The researchers compared the change in weight for non-smokers, continuing smokers and smokers who quit. "People tend to put on some weight over time and everyone in the study gained weight. The non-smokers gained about a pound a year for 10 years," said Veldheer.

The researchers then compared the weight gain in smokers who quit and smokers who continued smoking. What they found is that for smokers of fewer than 15 cigarettes per day, there was no significant difference in the 10-year weight gain between those who quit smoking and those who did not quit.

"This is good news for light to moderate smokers who are concerned about weight gain. It means that in the long term, quitting smoking will not make that big of an impact on their weight," said Veldheer.

However, for smokers of 25 or more cigarettes per day and those who were obese prior to quitting -- body mass index of 30 or more -- the amount of weight gain attributable to quitting was substantial. Smokers of 25 or more cigarettes per day reported 23 pounds of smoking cessation-attributable weight gain and obese smokers reported 16 pounds of weight gain that could be directly attributed to quitting.

"Although this may seem like a lot of weight, it is important for all smokers to remember that quitting smoking is the single most important thing they can do for their health," said Veldheer. "That being said, for heavy smokers and obese smokers, it may be a good idea to work on quitting smoking while also making other healthy lifestyle changes to control their weight."