Popular cult classics like The Big Lebowski would have you believe that people who use marijuana not only always have the munchies, but they’re also too lazy to engage in a lot of physical activity.
With those kinds of stereotypes pervading movies and TV shows, it makes sense that many people would assume marijuana use is positively associated with weight gain.
But a new study published last week in the International Journal of Epidemiology appears to undermine that belief. It’s the latest research to show that marijuana users are actually less likely to be obese compared to non-users.
For their work, Michigan State University researchers drew on data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a cross-sectional, nationally representative study sample of U.S. citizens aged 18 and older. In total, they looked at the reported responses of more than 33,000 people.
In the first wave of interviews completed in 2001-2002, participants were asked if they used cannabis and, if so, how recently and how frequently. When they returned for their follow-up interview in 2004-2005, researchers asked participants if they used cannabis since that first interview.
Between the two interview periods, researchers tracked an increase in body mass index (BMI) in all categories of respondents—those who’d never consumed, people who had discontinued past use, “initiates” or newbies and persistent users.
Once they excluded participants who were older than 65 (because research shows BMI declines in older people are often due to loss of muscle mass), they discovered “an attenuated BMI gain for cannabis-use subgroups when compared with never-users.”
In other words, those who reported using marijuana gained weight, but at a reduced rate compared to those who have never consumed cannabis.
“In NESARC, persistent cannabis users and the initiates were under-represented in stably obese subgroups,” the study states. “In addition, these same actively cannabis-using subgroups were under-represented among newly incident cases of obesity observed at W2.”
The study offers a couple of theories to explain why marijuana users experience lower weight gain. One, for example, has to do with how the density of a specific cannabinoid receptor (CB1R) decreases with chronic cannabis use. It’s a theory that was first introduced last year by a separate team of researchers at Indiana University South Bend.
“For many patients,” they wrote in the meta-analysis they published in December, “Cannabis may be a better option for weight loss than surgery or pharmaceuticals.”
Another possibility to explain the relationship between marijuana use and BMI has to do with the anti-inflammatory properties of another cannabinoid receptor, CB2R. “The association of inflammation and obesity is widely established in pre-clinical and clinical studies,” the study’s authors write.
These findings are important for future biomedical research regarding cannabinoids—especially since medical marijuana is often toted as a potential treatment for preventing weight loss in HIV and cancer patients, the study states.
The average cannabis consumer concerned about their waistline might also find a little bit of comfort in these results, too—especially since other research has indicated that states with legal marijuana saw an increase in junk food purchases.
Photo courtesy of Philip Steffan.