Smokers who quit really do gain weight-especially if they are already obese, according to a new study that followed people for eight years after they first tried to give up smoking.

“Someone may be at risk of much greater weight gain when they quit smoking the more overweight they are to start with,” lead investigator Dr. Deborah Lycett, of the University of Birmingham in the U.K., told Reuters Health via e-mail. But the findings should not discourage overweight or obese smokers from trying to quit, she added.

“I think that being forewarned is forearmed,” Lycett said. “If we know that there is a chance we might put on a significant amount of weight, we can prepare for that possibility, and be in a better frame of mind to deal with it, if it happens.”

Kicking the habit can clearly cause people to put on pounds, Lycett and her colleagues note in the journal Addiction, but few studies have assessed the relationship between a smoker’s starting body mass index (BMI, a measure of weight in relation to height used to gauge obesity) at the time he or she quits, and the amount of weight they end up gaining.

To investigate, Lycett and her team looked at 840 cigarette smokers who participated in a 12-week trial of the nicotine patch versus placebo in the 1990s. Over an eight-year follow-up period, eighty-five of them were confirmed to have been smoke-free since quitting during the patch trial, and were classified as abstainers. Most people-613 in total-kept smoking throughout the 8 years. Another 26 had managed to stay off cigarettes for the first year of the study but then relapsed. And 116 people kept smoking through the first year of the study but had subsequently quit and were nonsmokers eight years later.

The researchers verified the subjects’ abstinence at the end of the eight years by testing their breath for carbon monoxide or their saliva for the nicotine byproduct cotinine.

Nearly everyone, including the smokers, had gained some weight over the eight years, but those who had succeeded in quitting smoking put on significantly more. Just a quarter of them were at a healthy weight for their height, the researchers found.

Those who had abstained since the original patch trial gained an average of about 8.8 kilograms (nearly 20 pounds), while the current smokers gained just 2.2 kilograms (about five pounds). The relapsed smokers gained 3.3 kilograms (around 7 pounds), and late abstainers who had quit sometime after the original trial put on 8.3 kilograms (18 pounds).

But among abstainers, there were also big differences in weight gain depending on the subjects’ original BMIs. Both abstainers who started out underweight and those who were overweight (with average BMIs of 18 and 29, respectively) gained about 10 kilograms, or 22 pounds. Normal-weight people with BMIs of 23 gained slightly less, averaging 7.8 kilograms (17 pounds). But individuals who started out severely obese (BMI of 36) gained 19.4 kilograms, or more than 40 pounds.

For smokers, weight gain went in the opposite direction, with underweight people gaining the most (3.8 kilograms, or 8.5 pounds) and the heaviest people actually losing a bit of weight over time (0.8 kilograms, or about 2 pounds).

“Smokers are usually advised to quit first and deal with weight later, but new research is exploring how to tackle both together,” Lycett said. “One thing that does look promising is physical activity. We know that being physically active for an hour each day can help with weight control and there is also data suggesting that exercise reduces cravings to smoke too.”

Based on the findings, heavier smokers and their doctors should be vigilant about post-quit weight gain, she added. “They should keep an eye on their weight and be ready to make or support changes to their physical activity levels and the amount they eat as soon as they notice weight increasing,” Lycett said. “It is easier to lose a few pounds as soon as you notice, than to find you have a lot more to lose in a year’s time.”

She concluded: “Regardless of how much weight you gain, stopping smoking remains the single most important thing that someone can do for their health. We should never quit quitting.”

SOURCE:  Addiction, online October 6, 2010.