Smoke and mirrors: Marijuana users weigh less, despite the ‘munchies’

April 22, 2019

“Munchies” or not, people who like to get high on marijuana sustain a lower body weight than those who abstain, according to findings of a study conducted by researchers at Michigan State University and released on April 19.

The findings, published in the International Journal of Epidemiology, belie the belief that marijuana users ultimately gain more weight. Results also suggest that new and persistent users are less likely to be overweight or obese, overall.

“Over a three-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,” said Omayma Alshaarawy, lead author and an assistant professor of family medicine. “Our study builds on mounting evidence that this opposite effect occurs.”

Indeed, she said, “We found that users, even those who just started, were more likely to be at a normal, healthier weight and stay at that weight,” she said. “Only 15% of persistent users were considered obese compared to 20% of non-users.”

Researchers used data from the National Epidemiologic Survey of Alcohol and Related Conditions and looked at the Body Mass Index (BMI) of 33,000 subjects, ages 18 and older; then,  compared the numbers.

While the actual weight difference among users and non-users was modes— about two pounds for a 5-foot-7-inch participant who weighed close to 200 pounds at the start of the study—the variance was prevalent among the entire sample size.

“An average two-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,” Alshaarawy said.

So, what is it about marijuana that seems to affect weight? Alshaarawy indicated it’s still relatively unknown but it could be several factors.

“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 said. “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.”

Alshaarawy cautions, though, that marijuana should not be considered a diet aid.

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

Research contact:  alshaara@msu.edu

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