Anyone who smokes cannabis recreationally has made that regrettable midnight trip to Taco Bell, belly sloshing with grape soda and orange Cheeto dust caked up to the elbows. Know as the weed munchies, the hunger pangs caused by cannabis marijuana can be unbelievably strong at times.
For people undergoing chemotherapy or AIDS-induced anorexia, pot can simply help to have an appetite at all and keep food down.
Weed Munchies: Why does cannabis make you so hungry?
Though cannabis has been used for all sorts of therapeutic purposes since ancient times, it’s the plant’s appetite stimulant effect that kicked off the latest round of cannabis medicinal research starting in the 1960s and 70s. Perhaps the oldest FDA-approved marijuana-based medicine — Marinol (dronabinol) — is a synthetic distillate of tetrahydrocannabinol (THC), the main psychoactive component in pot.
Dronabinol is prescribed to cancer/chemotherapy and AIDS patients who have trouble eating because of nausea and vomiting.
Despite the growing body of research into using different strains and chemical isolates of cannabis to treat everything from epilepsy, to brain tumors, to chronic pain, to PTSD, the appetite stimulant effect of the drug is still its most widely touted and best-researched characteristic.
The cannabinoids in marijuana, namely THC, mimic the body’s natural cannabinoid neurotransmitters. These cannabinoids are part of a system of transmitters and receptors on the membranes of nerve cells that fit like keys in locks. Once the receptors bind with their corresponding chemicals, it sets off a cascade of different chemical responses that direct your body to function in a certain way, whether it increases your appetite, calms you for sleep, enhances your mood, or activates a stress response. This system is known as the endocannabinoid system.
The research community is well aware of the cannabinoid receptors’ role in appetite — specifically one type of receptor called CB1, which strongly interacts with THC and is most responsible for the marijuana high users describe.
How are cannabinoid receptors involved with appetite?
In the 2000s, pharma researchers in Great Britain targeted CB1 with an “antagonist,” or a chemical that blocks the CB1 receptor. (THC is a “partial agonist,” which means it activates the receptor, but in a slightly different way than the body’s natural cannabinoids).
The British drug Zimulti (rimonabant) targeted obesity and was initially wildly successful upon its 2006 release; reducing appetite in those who took it by blocking their CB1 receptors. Unfortunately, despite all the pounds shed, regulators yanked it from the market in 2008 before it hit the U.S.
It turns out rimonabant tended to make people depressed and suicidal, proving the endocannabinoid system is tied up with all sorts of important functions, including mood, aside from appetite regulation.
What is appetite and why does pot affect it?
How exactly does your body regulate appetite, and why does pot affect that? Appetite regulation in general is a complex physical and psychological process that scientists still don’t fully understand. But researchers are working out the chemical pathways by which THC and other cannabinoids interact with CB1 receptors to induce hunger.
One of the neural centers regulating hunger is the part of the brain called the hypothalamus. There are large concentrations of CB1 receptors here, as well as a specific neuron type called “pro-opiomelanocortin” neurons or POMCs.
POMCs secrete two, opposing substances, depending on the feedback they receive from other parts of the neural network. They are
- Alpha melanocyte-stimulating hormone, which we’ll just refer to as a “hunger-suppressing hormone” from now on, and
- Beta-endorphin, which we’ll call the “hunger stimulating hormone.”
A team of researchers released 2015 findings in the journal Nature that illuminates part of the chemical pathway by which cannabis makes you head to the fridge to finish off your absent roommate’s tub of rice pudding, irrespective of her guaranteed retaliation.
They let mice eat until they were full, then got them stoned on pure THC. The result was predictable: even though the stoned group wasn’t hungry when they started, those mice tended to take the proverbial Taco Bell ride to back to the food bowl more often than the sober control group. They had all the signs of weed munchies.
Turns out, cannabis compounds plugging into CB1 receptors stimulate the POMC cells to squirt out the hunger stimulating hormone. To make sure this was the cause of the stoned mices’ hearty appetite, they tried again with a group given both THC and a designer chemical to block POMC activity.
Sure enough, even though those mice were stoned, the artificial POMC suppression curbed their appetite until it was similar to the sober control mice.
What else affects hunger from weed smoking?
The 2015 study illustrates a relatively new finding, however, and there are other ways pot may increase your appetite. For instance, anatomical and physiological studies have shown a “gut-brain axis” – a massive bundle of nerves that run from the gut to the brain, nerves which are also thick with CB1 receptors.
Also, THC isn’t the only chemical that interacts with CB1 receptors in the gut; natural cannabinoids produced by the body, other less potent cannabinoids in marijuana, and even the active chemical in chili peppers have been shown to interact with these receptors in various ways.
Furthermore, it’s only been in the past decade that researchers have realized how important the microbiome (the millions of bacteria species in the gut) is to appetite, digestion, and even cognitive function. Virtually no research show how marijuana compounds affect so-called “gut flora,” if at all.
WEED MUNCHIES REFERENCES
Rimonabant Redux and Strategies to Improve the Future Outlook of CB1 Receptor Neutral-Antagonist/Inverse-Agonist Therapies
Sara Jane Ward and Robert B. Raffa
Hypothalamic POMC neurons promote cannabinoid-induced feeding
Marco Koch et al
“Appetite and energy balancing”
Rogers PJ and Brunstrom JM
Physiology and Behavior