One of the best-known side effects of smoking cannabis is “the munchies,” or an intense increase in appetite. One minute someone might feel full, and the next they appear ravenous.
This effect, known scientifically as cannabis-induced hyperphagia, is powerful enough that for regular marijuana users, it can even cause weight gain, a seven-year analysis found.
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The short answer is that tetrahydrocannabinol, or THC, affects the body’s endocannabinoid system. This network, found in both the brain and body, is made of naturally produced signaling molecules, called endocannabinoids, and their corresponding receptors. It helps regulate mood, stress, pain, memory, immune responses, and even appetite.
Endocannabinoids act “like a ‘dimmer switch,’ fine-tuning neural activity to maintain balance, or homeostasis,” Ryan McLaughlin, co-director of the Cannabis Research Center and associate director of graduate studies in neuroscience at Washington State University, told Live Science in an email.
The body produces endocannabinoids because the brain needs tight control over how strongly circuits activate, especially when responding to challenges like hunger, McLaughlin explained. Any disruption in this system is “linked to conditions like anxiety, depression and chronic pain, making this system highly relevant to mental and physical health,” he noted.
And because THC has phytocannabinoids that target the same endocannabinoid system, understanding it helps scientists sort out cannabis’s potential benefits and risks.
THC “hijacks” our appetite circuit
Of the 140 or more types of phytocannabinoids that cannabis plants produce, THC is one of the best known. “THC works by mimicking endocannabinoids and binding primarily to CB1 receptors in the brain,” McLaughlin said. Those CB1 receptors show up heavily in brain areas tied to craving and reward, including the hypothalamus, which helps coordinate hunger signals.
When a person is not smoking cannabis, the body’s endocannabinoids are usually released briefly and locally, nudging the system toward hunger in a controlled way. But when someone uses cannabis, “THC activates these receptors more broadly and for a longer period of time,” McLaughlin said. “In that sense, it ‘hijacks’ a system that normally fine-tunes neural activity.”
That “hijack” is what causes the munchies, as THC turns up the brain’s interest in food to more extreme levels for longer than normal.
“When THC activates CB1 receptors in these areas, it enhances the motivational value of food, essentially tricking your brain into thinking it is in an acute fasting state,” McLaughlin said.
The munchies isn’t about food type
That fasting state helps explain why the munchies don’t always look like a dessert binge. In a 2025 study co-led by McLaughlin and others at Washington State University and the University of Calgary, 82 adults ages 21 to 62 were randomly assigned to vape either 20 milligrams of cannabis, 40 milligrams of cannabis, or a cannabis placebo. People who vaped cannabis ate significantly more than those in the placebo group, but it wasn’t just junk food.
“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,” study co-author Carrie Cuttler, a WSU psychology professor, said in a statement. According to the researchers, water was also among the popular consumption choices.
To further test whether weed affected taste preferences, the researchers also ran tandem experiments in rats at the University of Calgary. The animals could access different foods but had to work for it by pulling a lever.
Sober rats that were already full tended to quit the task. But after ingesting THC, they behaved differently. “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,” study co-author Matthew Hill, a professor of medicine at the University of Calgary, explained in the statement.
Like their human counterparts, the rats were not picky. The researchers expected more interest in carb-rich foods because these foods trigger a release in dopamine, a neurotransmitter that induces a feeling of pleasure, but that’s not what they saw. “It just seemed to be any food,” Hill said.
Other things can trigger the munchies
While cannabis use is known to trigger the munchies, other factors that affect the endocannabinoid system can create the same effect.
“Sleep deprivation, stress, intense exercise, or just the sight or smell of food can strongly activate appetite circuits in the brain,” McLaughlin said.
However, THC takes things a step further. “What is unique about THC is that it enhances both hunger-regulating regions and reward circuits [in the brain], which together can amplify the biological drive to eat as well as the pleasure of eating,” McLaughlin added.
Given that THC and other phytocannabinoids are still highly regulated, challenges in understanding the munchies and other effects caused by these substances remain. “One big misconception is that the ‘munchies’ happens to everyone, every time,” McLaughlin noted. In reality, people’s responses vary depending on the THC dose, the person’s tolerance, the way the drug is ingested and a person’s individual bodily makeup.
“Much of what we know comes from self-report rather than tightly controlled laboratory studies measuring actual caloric intake, hormones, and neural activity,” McLaughlin said. “But as cannabis laws evolve and research access improves, I think that there will be more attention paid to understanding this phenomenon.”
This article is for informational purposes only and is not meant to offer medical or dietary advice.