You don’t need to have even touched marijuana to have heard about the munchies – the insatiable, gnawing hunger that prompts people to head downstairs to the kitchen at 3am and heat up pizza rolls.
And tear into some leftover fried chicken.
And maybe crack open that tub of ice cream, too.
But why does this happen? What is it about weed that prompts people to shovel food into their mouths in a frenzied episode that they look back on and regret the next morning?
According to a 2015 study published in Nature Neuroscience by researchers from the Yale School of Medicine, it all comes down to the neurons in your brain that control your appetite. The team used mice as their subjects and looked at the effects that tetrahydrocannabinol (THC – the main psychoactive component in marijuana) had on the rodents’ brains.
There are a few interactions that come into play here. An earlier study, also published in Nature Neuroscience, had established that THC binds to cannabinoid receptors called CB1s in the olfactory bulb, the part of the brain responsible for processing sensory input from the nose.
This results in making food aromas, and therefore flavours, more intense.
Meanwhile, pro-opiomelanocortin (POMC) neurons play a key role in reducing appetite when you’re full. The Yale team found that these same neurons that should be telling you to stop eating are instead doing just the opposite when THC comes into play.
“It’s like pressing a car’s brakes and accelerating instead,” said lead author Tamas Harvath. “We were surprised to find that the neurons we thought were responsible for shutting down eating, were suddenly being activated and promoting hunger, even when you are full. It fools the brain’s central feeding system.”
The CB1 receptors end up hitting a switch of sorts that prompts the neurons to produce ghrelin, a hormone that increases your appetite.
So, a recap – marijuana tricks your brain into thinking that you’re hungry, even if you’re not. At the same time, smells and flavours are more powerful, making eating that much more satisfying and rewarding. It’s quite the one-two punch. And like my cat confronted with the chance to plop down on my keyboard as I’m trying to type, the temptation is usually too great to resist.
But this isn’t just a simple fun fact, either – this hunger-inducing side effect also has some potential benefits that researchers have been looking into. For example, marijuana has been used to stimulate the appetites of patients going through cancer treatments.
Exciting as that is, odds are the average person isn’t concerned about using weed to bolster their appetites. So for most people out there, just remember that if you’re watching your diet, you’re in for one hell of a cheat day – and there isn’t much you can do about it.
Next time you find yourself elbows deep in that bag of salt and vinegar chips, chowing down like nothing else in life matters, you’ll know why.