One of the best-known effects of cannabis is that it can give you the munchies. This effect can be exploited to stimulate eating in Anorexia patients. Both clinical and preclinical data indicate that THC is a strong appetite stimulator. More research is required to refine appetite modulation by cannabinoids.
CB1 receptors may be upregulated in an attempt to compensate for reduced endocannabinoid signaling. In line with this, mutations in CB1 (the major cannabinoid receptor) and FAAH (the major endocannabinoid degrading enzyme) were found to be associated with Anorexia and Bulimia (Monteleone et al., 2009).
2AG and AEA are involved in food intake regulation (Fride, Bregman, & Kirkham, 2005).
CBG causes hyperphagia in animals without producing negative neuromotor side effects (Brierley, Samuels, Duncan, Whalley, & Williams, 2016). Also, CBG-BDS acts as an appetite stimulant, probably through CB1 receptors (Brierley, Samuels, Duncan, Whalley, & Williams, 2017).
Brierley, D. I., Samuels, J., Duncan, M., Whalley, B. J., & Williams, C. M. (2016). Cannabigerol is a novel, well-tolerated appetite stimulant in pre-satiated rats. Psychopharmacology, 233(19-20), 3603-3613. https://doi.org/10.1007/s00213-016-4397-4
Brierley, D. I., Samuels, J., Duncan, M., Whalley, B. J., & Williams, C. M. (2017). A cannabigerol-rich Cannabis sativa extract, devoid of [INCREMENT]9-tetrahydrocannabinol, elicits hyperphagia in rats. Behavioural Pharmacology. https://doi.org/10.1097/FBP.0000000000000285
Fride, E., Bregman, T., & Kirkham, T. C. (2005). endocannabinoids and food intake: newborn suckling and appetite regulation in adulthood. Experimental Biology and Medicine (Maywood, N.J.), 230(4), 225-234.
Monteleone, P., Bifulco, M., Di Filippo, C., Gazzerro, P., Canestrelli, B., Monteleone, F., Proto, M.C., Di Genio, M., Grimaldi, C., and Maj, M. (2009). Association of CNR1 and FAAH endocannabinoid gene polymorphisms with Anorexia nervosa and Bulimia nervosa: evidence for synergistic effects. Genes Brain Behav. 8, 728–732.
In line with theory, THC was found to induce eating, allowing anorexic patients to gain weight (Andries et al., 2014).
Andries, A., Frystyk, J., Flyvbjerg, A., and Støving, R.K. (2014). Dronabinol in severe, enduring Anorexia nervosa: a randomized controlled trial. Int. J. Eat. Disord. 47, 18–23.