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.
For help quitting smoking, visit the American Lung Association.
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