Pretty much everyone who has tried marijuana can attest to the drug’s temporary effects on appetite — the so-called “munchies” that strike after smoking or ingesting pot. So you might think that it’s pretty clear that between marijuana’s calming effects (it’s not known for inciting a compelling need to exercise, after all) and its appetite-stimulating properties, cannabis is likelier to lead to weight gain over time. But that link isn’t as straightforward as that. “There’s key information that’s still missing in order to fully understand the association between cannabis consumption and weight gain,” says Emily Dubé, a graduate student in the department of social and preventive medicine at the University of Montreal, in Canada, and one of the lead researchers of a new study in the journal Pharmacology Biochemistry and Behavior.
For one thing, many pot smokers also smoke tobacco cigarettes and nicotine is known to suppress appetite. Then there are gender differences. Nicotine and THC, the main psychoactive ingredient in marijuana, don’t affect brain circuits that control hunger the same way in both men and women. Researchers speculate that female hormones play a role. (On a related note, a recent study in the journal Obesity shows that women may be more likely than guys to have the munchies after drinking alcohol. That’s because booze increases the brain’s sensitivity to external food cues, like aroma, prompting women to eat more.)
The Link Between Marijuana and Weight
In the study, which used data from 1,294 young men and women, Dubé and her colleagues concluded that long-term pot use does indeed lead to weight gain. “We were surprised to find that in men who smoke cannabis but do not smoke [tobacco] cigarettes, increasing cannabis consumption leads to increased weight gain,” explains Dubé. But for men who smoked cigarettes, the reverse was true: The guys didn’t put on extra pounds, even though they used marijuana. Weight gain for women appeared similar to that of non-smoking males, she adds.
The researcher and her colleagues used data from the Canadian Nicotine Dependence in Teens (NDIT) study, which provided information about diet, weight and height, physical activity level and frequency of cannabis, nicotine and alcohol use of 1,294 teens, starting at ages 12 and 13 and following them into young adulthood.
Previous studies, though, have found no association between cannabis use and BMI (body mass index); others have even touted the drug for its weight-loss benefits. A 2013 study in the American Journal of Medicine, for example, showed that cannabis users had lower insulin levels and waist circumference, making them less susceptible to dangerous visceral belly fat. “Our study highlights the need to re-examine the question and consider tobacco as an important variable,” says Dubé. “Having a better understanding of an individual’s [combined] cannabis and cigarette use could be used to better understand addiction patterns … and, thus, be used to better counsel individuals.”