Taking a pill called naltrexone (ReVia) when they stop smoking could help women keep dreaded weight gain at bay, according to new research.
Researchers analysed two earlier studies that compared the quit rates and weight gain among heavy smokers who received either naltrexone - a drug used to treat addiction - or an inactive placebo, along with a nicotine patch and weekly counselling while trying to quit smoking.
Although the groups taking naltrexone had higher quit rates at the end of four- and six-week treatment courses, participants who took the drug were no more likely to remain abstinent after 12 months.
But women who took naltrexone gained significantly less weight six and 12 months after they quit smoking than women who received the placebo, according to the study, published in the December issue of Biological Psychiatry. However, this difference was not observed for men.
"Weight gain is a crucial issue for people, especially women who have societal pressure and can be more discontented with their bodies," said Andrea King, a professor of psychiatry and behavioural neuroscience at the University of Chicago and lead author of the current study.
"Even if naltrexone doesn't help quit rates, if we could break down that barrier, it could have an impact," King added.
More than 80% of people who quit smoking gain weight, and the average weight gain is between five and 4kg, according to the study. However, as many as one-quarter of quitters gain more than 4kg.
Weight gain during smoking cessation is usually modest and not a serious health problem compared to the health benefit of quitting smoking, said Dr Norman Edelman, chief medical officer of the American Lung Association.
"[But] people, especially young women, would be more likely to get involved in smoking cessation programs if there were some way to control their weight gain so in terms of that, I think [naltrexone] is important," Edelman said.
People who want to quit smoking and are worried about gaining weight should talk with their doctor about naltrexone, he suggested.
Both issues can be deadly. Tobacco is the leading cause of preventable deaths in the United States, and obesity is second, the study authors noted.
King pointed out that naltrexone would probably not take the place of the first-line treatments for quitting smoking, which are the antidepressant bupropion (Zyban), in some cases together with a nicotine patch such as Nicoderm or the drug varenicline (Chantix).
However, naltrexone, along with a nicotine patch and counselling, could be an option for those who did not have success with these treatments or who have serious concerns about weight gain, King said.
The side effects associated with naltrexone are generally mild and rare, King said. Nausea, dizziness and fatigue are most common, and often overcome by taking the once-a-day medication with food or at bedtime, she added.
For the current study, King and her colleagues analysed the results of studies done at the University of Chicago and Yale University in New Haven, Conn.
The Chicago study involved more than 300 adults who smoked between 10 and 40 cigarettes a day for at least the past two years. During the four-week treatment, participants took either naltrexone or the placebo, used Nicoderm and received behavioural and cognitive counselling.
The Yale study had nearly 400 adults who smoked 20 or more cigarettes a day for at least the past year. It was similar to the Chicago study, except the researchers tested a six-week treatment course and three doses of naltrexone along with placebo.
Women who took naltrexone gained an average of about 3kg and 5kg six and 12 months after treatment, respectively, whereas the women who received placebo gained an average of about 5 and 7kg, respectively, the researchers found.
In addition, a slightly smaller proportion of women taking naltrexone increased their body weight by 7% or more, which the US Food and Drug Administration (FDA) considers clinically significant weight gain.
The men in the study gained less weight on average than women, and these gains were a smaller percentage of their original body weight, which could have made it more difficult to detect lower weight gain among men taking naltrexone, King said. More research is needed on this group, she added.
It is not clear why women seem to be more prone to weight gain when they quit smoking than men.
"I think of women smoking more for emotional regulation and management, and potentially without that crutch, they may turn to high sweet and fat foods more than men," King said.
Naltrexone is thought to block the effects of opioids in the body, which could reduce cravings for sweet and fatty foods, King noted.
In addition, giving up cigarettes leads to drops in metabolism that can cause quitters to put on pounds no matter what they eat, King pointed out.
King encourages people trying to quit to eat sensibly and exercise, which can help reduce the stress of quitting, but not to diet, which can make quitting even more difficult.
"If there are times when you're going to have a candy bar or a cigarette, a candy bar is better, and don't beat yourself up about it," King said.
Naltrexone is not approved by the FDA for smoking cessation and is instead used off-label for this indication. It is approved to help people overcome alcohol and drug addictions.
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For help quitting smoking, visit the American Lung Association.
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