PULLMAN, Wash. - The urgent onset of "the munchies" after cannabis use isn't imaginary - it's a cognitive response that occurs regardless of sex, age, weight or recent food consumption and could offer clues to help people struggling with appetite loss.
Those findings from a collaborative study, conducted by researchers at Washington State University and the University of Calgary, were recently published in the Proceedings of the National Academy of Sciences (PNAS).
"There are a lot of different diseases, conditions and disorders associated with wasting syndromes and lack of appetite, and this study really supports the idea that cannabis can be used medicinally to increase appetite in people who have conditions like HIV, AIDS, or who are on chemotherapy," said Carrie Cuttler, a WSU psychology professor.
Led in part by Cuttler, who directs The Health and Cognition (THC) Lab at WSU, and College of Veterinary Medicine professor Ryan McLaughlin, the research was conducted in tandem with Calgary researchers Matthew Hill and Catherine Hume, who ran a similar series of studies using a rat model.
The human clinical trial examined 82 volunteer subjects aged 21 to 62 from the greater Pullman, Wash., community. Each participant was randomly selected to vape either 20 or 40 milligrams of cannabis or a cannabis placebo, the latter of which served as the control group.
"The human study found irrespective of body mass index, time of last food consumption, sex or how much cannabis was consumed, human participants who used cannabis during the trial ate significantly more food," McLaughlin said.
Of all the food options - spanning carbohydrates to protein to fatty snack foods - some appealed more than others.
"Beef jerky was one of the No. 1 things intoxicated people gravitated toward, which I don't understand. Honestly, I would have thought chocolate, chips, Rice Krispies treats - things like that," Cuttler said, noting water was also high on the list of desirable items.
The study examining appetite in rats at the University of Calgary yielded similar findings. Like the human participants, rats were exposed to cannabis in a controlled environment and provided with multiple food options, which they were tasked with pulling a lever to be rewarded food. No matter what the food was, rats that were under the influence consistently pulled levers.
"The sober animals are kind of like, 'I'm full. Why do I care?' They don't put in any effort at all. They barely work in any capacity to get access to food. But you get them stoned again, and even though they're now full and they've eaten, they go right back as if they're starving," Hill said.
The study found that the rats' food preference did not matter.
"The same thing we saw in the humans we saw in the rats. We kind of thought it would make them want to eat carb-rich foods, but that didn't seem to be the case. It just seemed to be any food," Hill said.
The study is significant because, on a subject with little scientific support, it helps highlight the physiological mechanisms responsible for appetite stimulation.
The study is significant because, on a subject with little scientific support, it helps highlight the physiological mechanisms responsible for appetite stimulation.
Endogenous cannabinoids, also called endocannabinoids, are naturally produced by the body to regulate mood, memory, pain, immune responses and appetite in order to maintain balance.
"That's what the natural endocannabinoid system does in the hypothalamus," McLaughlin said. "But THC hijacks that entire system. So even though you're not necessarily hungry, THC can stimulate cannabinoid receptors in the brain and make you feel hungry."
The stimulation of those cannabinoid receptors in the brain is another key finding from the research. Pharmacology studies at the University of Calgary that blocked cannabinoid receptors in the peripheral nervous system in rats didn't curb appetite, but blocking those same cannabinoid receptors in the brain did.
"That's what really gives us the opportunity to look at whether this is something brain-mediated or gut-mediated, and this generally shows 'the munchies' are mediated by the brain," McLaughlin said.
Knowing hunger stems from receptors in the brain, researchers hope the study can inform future treatments for people experiencing appetite loss.
"There's very little documentation of the munchies phenomenon, but this paper really starts to tap into some of the mechanisms that might be responsible," Cuttler said.
