Most people are familiar with “the munchies,” the sudden urge to eat after using cannabis. New research suggests that response is not just cultural lore. It reflects a measurable shift in how the brain processes food.
A study published in Proceedings of the National Academy of Sciences found that cannabis increases food intake in both humans and rodents by altering reward valuation and motivation for food. The effect occurred regardless of body mass index, sex, age or how recently someone had eaten.
“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,” said Ryan McLaughlin, a professor in Washington State University’s College of Veterinary Medicine and co-author of the study.
In the human clinical trial, 82 adults ages 21 to 62 were randomly assigned to vape either cannabis or a cannabis placebo. Participants who received cannabis consumed significantly more food than those in the control group.
Researchers also observed that the increased intake was not limited to specific food types. While some intoxicated participants gravitated toward items like beef jerky and water, the overall pattern showed increased consumption across food categories.
Parallel experiments in rats produced similar results. Rats exposed to cannabis worked harder to obtain food, even when they were already full.
“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,” said Matthew Hill, a researcher involved in the rodent studies.
To understand why this happens, researchers examined the body’s endocannabinoid system, a network of receptors involved in regulating mood, pain, memory and appetite. Tetrahydrocannabinol, or THC, the primary psychoactive compound in cannabis, activates cannabinoid receptors in the brain.
“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.”
Additional pharmacology experiments showed that blocking cannabinoid receptors in the peripheral nervous system did not reduce cannabis-induced eating in rats. Blocking those same 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.
The findings may have implications beyond recreational use. Loss of appetite is common in people undergoing chemotherapy or living with chronic conditions such as HIV and AIDS.
“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,” said Carrie Cuttler, a psychology professor at Washington State University.
The study does not examine long-term effects of cannabis use or recommend cannabis as a first-line medical treatment. Instead, it helps clarify how THC influences the brain’s hunger and reward systems in the short term.
For researchers studying appetite regulation, the work adds to a growing understanding that hunger is not driven only by stomach signals. Brain circuitry involved in motivation and reward also plays a central role in when and why people eat.
This work was supported by operating funds from the Canadian Institutes of Health Research and the Natural Sciences and Engineering Research Council of Canada. Additional support came from the University of Calgary, Alberta Children’s Hospital Research Institute, Brain Canada and Alberta Innovates. Human studies were supported in part by funds provided for medical and biological research through Washington State Initiative Measure No. 502. One author also received support from the National Institutes of Health.