Rates of obesity are about one-third lower in people who smoke marijuana at least three times a week compared with people who are not marijuana smokers, French researchers have found.

The researchers analyzed data from two large national surveys of Americans, which included a total of 52,000 people. In the first survey, they found 22 percent of people who did not smoke marijuana were obese, compared with 14 percent of people who smoked marijuana regularly. In the second survey, they found 25 percent of those who didn’t smoke marijuana were obese, compared with 17 percent of regular marijuana smokers, Time reports.

The article notes the study results do not prove marijuana smoking itself keeps a person’s weight down. Other factors could be responsible. For instance, some of the people in the survey might have been ill with cancer or AIDS, and smoked marijuana to stimulate their appetite. These patients are much less likely to be obese than the general population. Many studies have shown smoking marijuana increases appetite, at least in the short-term, making it an unlikely diet aid, the article adds.

The results are published in the American Journal of Epidemiology.