New research finds that, despite the common phenomenon of having “the munchies” after using marijuana, cannabis users tend to weigh less and are less likely to be obese.

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New research finds a surprising correlation between marijuana use and lower weight.

Recent surveys estimate that over 22 million people in the United States ages 12 and above regularly use cannabis and that more and more adults and seniors are taking up the habit.

Most of the adults who consume marijuana regularly do so for recreational purposes. Almost 90 percent of U.S. adult cannabis users say that they use it recreationally, while only the remaining 10 percent use it for medical purposes.

One of the physiological effects of marijuana is an increased appetite, or what is popularly referred to as having the munchies.

Although it may seem intuitive that an increased appetite would lead to weight gain, current existing epidemiological studies suggest that marijuana users are less likely to have obesity.

So, a team of researchers from Michigan State University (MSU), in East Lansing, set out to investigate this matter further, investigating whether people who regularly consume marijuana are more likely to gain weight.

Omayma Alshaarawy, Ph.D., an assistant professor of family medicine at MSU, led the new research, which appears in the International Journal of Epidemiology.

Alshaarawy and colleagues examined data from a prospective study called the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).

NESARC included 33,000 U.S. participants ages 18 and older who completed computer-assisted interviews about their cannabis use and their body mass index (BMI) between 2001 and 2005.

The researchers applied general linear modeling to study the relationship between BMI and marijuana use.

By the end of the NESARC study period, 77% of the study participants had never smoked cannabis, 18% had quit, 3% were just starting, and 2% were “persistent users.”

The current study found that overall, marijuana users were less likely to be overweight or have obesity.

“Over a 3-year period, all participants showed a weight increase, but interestingly, those who used marijuana had less of an increase, compared to those that never used,” reports the study’s lead author.

Alshaarawy acknowledges that the results of the study may seem counterintuitive, given that marijuana increases appetite. “Our study builds on mounting evidence that this opposite effect occurs,” she says.

Lower BMI was found among both new and persistent users.

We found that users, even those who just started, were more likely to be at a normal, healthier weight and stay at that weight. […] Only 15% of persistent users were considered obese, compared to 20% of nonusers.”

Omayma Alshaarawy, Ph.D.

The researcher goes on to explain that, while the difference in BMI between marijuana users and nonusers wasn’t very big, it is significant that the researchers found this trend among the entire sample size.

“An average 2-pound difference doesn’t seem like much, but we found it in more than 30,000 people with all different kinds of behaviors and still got this result,” says Alshaarawy.

Although this study is observational and cannot infer causality, the lead investigator ventures some opinions as to the mechanisms that may explain the association between a lower BMI and marijuana consumption.

“It could be something that’s more behavioral, like someone becoming more conscious of their food intake as they worry about the munchies after cannabis use and gaining weight,” she says.

“Or it could be the cannabis use itself, which can modify how certain cells, or receptors, respond in the body and can ultimately affect weight gain. More research needs to be done,” concludes the researcher.

Until we know more about the underlying mechanisms, however, Alshaarawy warns against the dangers of using marijuana to lose weight.

There [are] too many health concerns around cannabis that far outweigh the potential positive, yet modest, effects it has on weight gain. […] People shouldn’t consider it as a way to maintain or even lose weight.”

Omayma Alshaarawy, Ph.D.