Weight-conscious smokers may now have fewer reasons not to quit their habit, according to a new study in the Archives of Internal Medicine.

In the four-year study, published last week, researchers at the Yale School of Medicine examined the effects of a treatment combining an opiate drug and a nicotine patch on 400 individuals attempting to quit smoking. Researchers examined the effects of the drug, naltrexone, on the weight gain traditionally associated with smoking cessation, said Stephanie O’Malley, a psychiatry professor at the Yale School of Medicine and lead author of the study.

“Our hypothesis that naltrexone would reduce weight gain was confirmed and occurred in the lower doses,” O’Malley said. “We found evidence suggesting that the higher dose may be effective for helping people quit smoking, but these results need to be confirmed through further testing.”

O’Malley, the principal investigator at the Transdisciplinary Tobacco Use Research Center at Yale, tested the efficacy of three doses of naltrexone — 25 mg, 50 mg and 100 mg daily — along with a placebo, combined with a nicotine patch, in helping subjects to kick their smoking habit.

Weight gain is a side effect of quitting that deters many smokers from attempting to stop, said Robin Mermelstein, professor of psychology and director of the Center for Health Behavior Research at the University of Illinois, Chicago.

“For many women, the fear of weight gain … may keep them from even trying to quit, or they may go back to smoking after they quit if they start to gain weight,” Mermelstein said.

She also said that although weight gain upon quitting smoking is variable, it is common for former smokers to gain about 5 pounds, and some may gain more.

O’Malley also said that while most trends show a reduction in smoking nationwide, fewer women than men attempt to kick the habit. Caryn Lerman, director of the TTURC at the University of Pennsylvania, said this pattern is most likely due to the fact that the fear of weight gain is more prominent in females than in males.

Research suggests that both food and smoking can have similar effects on the brain’s reward pathways, and people tend to increase their intake of foods high in fat and sugar when trying to quit smoking, Lerman said.

Naltrexone works by blocking the brain’s opiate receptors — the receptors involved in reinforcing the value of some food and drugs, O’Malley said. By blocking these receptors, she said, naltrexone may block the reward value of foods that stimulate the brain

O’Malley’s research is significant in the scientific community because few other FDA-approved treatments for nicotine dependence are available, and about 75 percent of smokers relapse after trying to quit, Lerman said. Because the results of the study suggest that low doses of naltrexone may help reduce weight gain after quitting smoking, O’Malley said she hopes her results will increase smokers’ desire to quit.

“We hope that the results could be used to help those individuals who are weight-concerned have another option that would make quitting smoking more acceptable to them,” O’Malley said.