Scientists have long known the role of cannabinoids in appetite regulation. For example, THC increases appetite, while Ribomant (a selective CB1 receptor agonist drug, which regulators approved in Europe in 2006) was an effective anti-obesity drug. However, the maker withdrew it in 2008 due to serious side effects. In addition, Epidiolex (pure CBD) is an FDA-approved medication to treat cancer- and AIDS-related anorexia.
Several studies have evaluated the prevalence of obesity among cannabis users, and the results are equivocal. Some studies found lower prevalence of obesity among cannabis users than among non-users. Other studies, however, found more obesity among regular cannabis smokers. Moreover, further studies found that while cannabis users had higher intake of calories, they did not have higher body mass indexes (meaning: they were heavier built relative to their height).
However, a higher number of studies involving more people show that cannabis users are less obese than non-users.
Watch this 3:31 minute video by the Carilion Clinic: “All About Obesity”
In animal experiments, rats, mice, and dogs ate more when they received THC. Interestingly though, long-term administration of THC did not lead to becoming overweight. As a matter of fact, those animals that consumed THC for a long time (some as long as 2 years), ended up losing weight, but they regained that weight once they stopped consuming THC.
Having said that, other experiments show that the weight gain after stopping THC is much slower when the animals had consumed both THC and CBD. In addition, those animals whose food was enriched with CBD gained much less weight than animals that ate regular food.
Several studies show that THC acts as an antagonist, and its affinity to the CB1 receptor is similar to that of anandamide (AEA). As such, scientists’ hypothesis that THC leads to a differential reduction in the different types of fat tissues (e.g. gut fat vs skin fat). Indeed, recent studies found an endocannabinoid overactivity in visceral obesity.
Scientists believe in an adaptive downregulation of the endocannabinoid signaling in connection with THC. While short-term administration of THC increases appetite (agonist effect), it desensitizes CB1 receptors, which on the long run results in an antagonist effect (appetite suppression and therefore weight loss).
Furthermore, other non-THC cannabinoids, such as CBD and THCV might also contribute to weight loss and complement the weight-loss effect of THC.
Watch this 2:16 minute video by KPRC: “Marijuana and weight loss”
The main issue regarding cannabinoids and weight loss is how one can achieve a peripheral effect (meaning: in the guts) without central (meaning: in the brain) side effects. The point is to be able to find such peripheral CB1 antagonists that do not have psychiatric side effects in the brain.
As we can now see, chronic THC administration downregulates peripheral endocannabinoid signaling.
Alone in the United States, 40% of adults are obese (with a BMI of 30 or above), while another 32% is overweight (with a BMI between 25-29.9). Obesity contributes to 13% of overall mortality. Therefore, it is important to find safe ways of reducing overweight and preventing weight gain.
What we discussed above suggests that THC and/or a combination of THC and CBD might be effective in improving metabolic disorders and doctors could use them to treat obesity and overweight. Some health professional believe that those FDA approved cannabinoid medications that are currently used to treat nausea, might also be used off-label to treat obesity.
They caution, however, that smoked cannabis might not be the best way to reduce weight, because the risk associated with smoke inhalation might counterbalance the benefits. Furthermore, since there is an association between cannabis exposure and psychosis, THC-based medications might not be appropriate for people who have a history of or a genetic susceptibility to mental illness.
Future studies, therefore, should investigate not only the effectiveness of cannabinoid-based weight loss medications, but also their safety regarding any potential psychiatric side effects.
Watch this 2:16 minute video by KSNV News 3 Las Vegas: “Skinny pot: Can some strains of marijuana trigger weight loss?”
Le Foll B, Trigo JM, Sharkey KA, Le Strat Y. Cannabis and Δ9-tetrahydrocannabinol (THC) for weight loss? Med Hypotheses. 2013 May;80(5):564-7.