While marijuana research is discovering new insights about cannabis, we should not forget about the characteristic effects of pot. The stereotypical behaviors that once were regulated to "potheads". The "munchies" are a prime example of this. Get high, eat a carton of Oreos, pass out. You would think that this would increase weight in marijuana users, but a recent study out of Michigan State University has found that the "munchies" (or rather, the ingestion of marijuana which precludes the munchies) actually correlates with weight loss.
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Dr. Omayma Alshaarawy and colleagues published their findings looking at 3 years worth of data on smokers and non-smokers (of marijuana) and their weight. The data are published in the International Journal of Neuroendriconology. While it seems common sense that marijuana, through its appetite-stimulating effect, would cause indices of weight to go up (e.g. body mass index [BMI]), this actually has not been seen in the clinic. The current study, with its longitudinal approach, is the latest piece of clinical evidence to support previous studies which suggest a weight decreasing effect of marijuana smoking (or vaping).
The current study found that, of all their participants, 15% of persistent users were considered obese compared to 20% of non-users. This finding is statistically significant, even though a 5% decrease in the incidence rate of obesity seems low. This translates to about a 2-pound difference, which may also seem pretty low, effect size speaking. However, as Dr. Alshaarawy told EurekaReport.org, "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".
There are many other studies that suggest that marijuana (in spite of the munchies) may lower weight compared to non-smokers. Another longitudinal study reported results that corroborate Dr. Alshaarawy's findings. In that study, the researchers found a negative correlation between BMI and marijuana use. Recent animal studies have also indicated that marijuana could decrease weight. In one study, cannabidiol (CBD), the nonpsychotropic chemical extracted from the cannabis plant, decreased weight in rats compared to controls.
Possible mechanisms for this effect have been suggested. The endocannabinoid receptor CB2 may be involved. In the CBD study, blocking CB2 receptors actually blocked weight loss. CB2 receptors are involved in many processes within the body. They are expressed in the brain but also outside of the nervous system. The CB2 receptor is thought to regulate metabolism. Peripheral CB1 antagonists or inverse agonists (which act similar to an antagonist) have shown to reduce body weight, adiposity, insulin resistance and dyslipidemia in animal models of obesity.
These are some of the possible mechanism behind these seemingly counterintuitive findings. Nevertheless, it does not mean you are free to munch on anything you want when you are using marijuana. As Dr. Alshaarawy cautions, "There [are] too many health concerns around cannabis that far outweigh the potential positive, yet modest, effects it has on weight gain," She went on to say. "People shouldn't consider it as a way to maintain or even lose weight." Back to the Stair Master, I guess.