July 11, 2012 -- As more people quit smoking cigarettes to protect their health, many face a new battle: weight gain. A new study in the journal BMJ shows that quitters gain more weight than anyone previously thought.
The research found that those who quit smoking gained an average of 10 to 11 pounds after 12 months, with most of the weight gain in the first three months.
Still, that shouldn't stop people from kicking the habit for good, the researchers said.
Scientists from France and the U.K. conducted a meta-analysis that examined 62 European-based studies of weight gain among people who had successfully stopped smoking. They said the average weight gain was higher than doctors generally thought, though there were substantial differences among study participants.
Until now, the National Institutes of Health in the U.S. has been saying that not everyone will gain weight after quitting, and those who do will generally gain fewer than 10 pounds.
"Most of the post-cessation weight gain occurs quickly, during the first quarter," said Henri-Jean Aubin, an addiction specialist who was lead author of the study. "Weight gain decelerates afterwards. There is a great inter-individual variability of post-cessation weight gain."
About 16 percent of people actually lost weight after quitting, and 13 percent gained more than 22 pounds. Because of the great range, researchers said the average weight gain is not necessarily meaningful to people kicking the cigarette habit.
Researchers said the study results should encourage physicians to acknowledge the risk of added pounds. Doctors need to encourage their patients to adopt a healthy diet and to exercise regularly, they said.
"On the other hand, weight-concerned smokers should consider the possibility they may not gain weight while quitting smoking," said Aubin.
This type of meta-analysis has its limitations because investigators did not measure participants' weights directly, but, rather, studied a collection of studies, said Robert Amler, dean of the School of Health Sciences at New York Medical College.
"Each of the collected studies weighed different groups of people [with] different ages, different baseline weights, different ethnicities under different circumstances, which means that each study yielded results that may imply something different than the others' results," said Amler.
No matter, "as a registered dietitian, this study does not change how I view the importance of smoking cessation," said Connie Diekman, director of University Nutrition at Washington University at St. Louis.
Nicotine boosts the metabolism, so when it is gone, the metabolism slows, thus leading to weight gain.
"There is also the 'I need something in my hands [or] mouth' feeling that smokers struggle with when they stop," said Diekman.
But quitting smoking takes priority. Experts said they would urge people to kick the habit, then worry about whether they'll gain weight. If people do need to change their eating habits drastically to get healthier, Diekman recommended doing that before quitting smoking, rather than trying to do both at the same time.
"Change is hard," she said.