NEW YORK - People who smoke marijuana may be prone to "the munchies," but surprisingly, they are less likely than non-smokers to pack on the pounds, suggests a recent study from France.
Analyzing data covering more than 50,000 American adults, researchers found that roughly 14% to 17% of the people reporting that they smoked pot at least three days per week were obese. That compared with a 22% to 25% obesity rate among people who said they had not used pot in the past 12 months.
"Initially, we thought we made a mistake," said Dr. Yann Le Strat, a psychiatrist at the Louis-Mourier Hospital in Colombes, France. He and co-author Dr. Bernard Le Foll had to check the results several times to make sure they were correct, Le Strat said.
"This is only a preliminary result," Le Strat told Reuters Health. "It doesn't mean that marijuana does actually help you lose weight, but perhaps there is a component that does."
The study, published in the American Journal of Epidemiology, included two surveys of US adults - one covering 43,000 people, the other about 9,300 respondents. Both had been conducted by branches of the US National Institutes of Health between 2001 and 2003.
The larger of the surveys found 14% of pot smokers were obese compared to 22% who didn't smoke pot. Similarly, the smaller survey found 17% of pot smokers to be obese compared to 25% of non-smokers.
Of all respondents to both surveys, between 4% and 7% said they smoked pot at least three times a week.
Whether or not they smoked cigarettes as well had no influence on the obesity findings.
The researchers did not look at whether diet and exercise habits were different in pot smokers and non-smokers.
According to another recent survey, from the Substance Abuse and Mental Health Services Administration, pot use is on the rise in the US Almost 18 million Americans used marijuana in 2010, an increase from about 15 million in 2007.
Scientists have researched the role of various molecules within marijuana smoke that produce the high feeling, block pain, and may underlie the hunger for food typically provoked by pot use.
Cannabinoids, molecules similar to natural signaling chemicals in the body, are believed to be key to stimulating appetite. So much so that in 2006, a drug called Rimonabant, designed to work against cannabinoids, was developed.
Rimonabant was approved in more than 30 countries -- but not in the US -- for the treatment of obesity. But the drug was pulled off shelves two years later because of an increased risk of suicide among users.
Whether cannabinoids are the only appetite stimulants in pot smoke, or whether other chemicals might account for the effect, remains to be seen the researchers say.
In the meantime, Dr. Vincenzo Di Marzo, a professor at the Institute of Biomolecular Chemistry in Pozzuoli, Italy, who was not part of the study, wasn't at all surprised by its results. "There's no evidence that repeated marijuana use can increase body weight."
Di Marzo cautions that the study does not show that smoking pot helps you lose weight, but he does believe it's a starting point for future research.
Le Strat echoed the sentiment and also warned against experimenting with pot as a diet aid.
"I see people living with marijuana dependence," Le Strat explained. "I hope people don't interpret the results to mean that if they use marijuana, they'll lose weight."