Breaking down ‘The Munchies’

How does science explain the appetite-stimulating side effects of cannabis use?

Photo by Giorgio Trovato on Unsplash

The munchies are a well-known side effect of cannabis use that can be a double-edged sword. Sometimes it catches users off guard and results in uncontrollable couch-locked snack binging. But for many medical users like cancer, chemotherapy and eating disorder patients, the munchies can be a much-needed appetite stimulant. 

But what are the munchies, according to science? 

The leading hypothesis has to do with human beings’ endocannabinoid system and a specific receptor called CB1. Molecules within the system send chemical messages throughout the body and brain by interacting with their receptors. And CB1 is known to play a significant role in a person’s energy homeostasis and food intake — and by extension, one’s ability to taste and smell.

A study published in Science Signaling in 2005 was one of the first to suggest this idea. It argued that THC alters and affects the metabolism via the CB1 receptor and can control food consumption by “modulating the inputs to various brain areas that monitor energy balance and by increasing the hedonic or reward value of the food consumed.” 

More recent research from the University of Oregon published in Current Biology in May 2023 put that theory to the test by getting worms high. Researchers from UO’s College of Arts and Sciences used a specific species of bacteria-eating worms (C. elegans) for the experiment. Cannabis had just been recreationally legalized in Oregon when the scientists began this experiment in 2014. 

“We thought, well heck, let’s just try this … We thought it would be amusing if it worked,” says lead scientist Shawn Lockery, a professor of biology and neuroscience at UO.

They soaked worms in an endocannabinoid known as Anandamide, which activates the endocannabinoid system. The worms were then placed in a simple T-shaped maze with high-quality food (i.e. bacteria) on one side and lower-quality food on the other. 

In this study, the higher-quality food was comparable to human junk food with lots of calories. The worms obviously preferred the higher-quality food both while “high” and in the control group. 

However, after they’d been soaked in Anandamide, that preference became much stronger. The worms swarmed the higher-quality food in greater numbers and stayed there for much longer than they had while sober. The worms were acting on a short-term survival impulse but not necessarily a healthy preference in the long term. 

“We suggest that this increase in existing preference is analogous to eating more of the foods you would crave anyway,” Lockery said in an OU press release on the study. “It’s like choosing pizza versus oatmeal.”

The researchers point out that the endocannabinoid system that’s affected in worms (and in humans) when under the influence is what controls the impulse of a starving animal when they seek out high-fat and high-sugar-content food. This would explain why cannabis users experiencing the munchies crave food that’s packed with fats and sugars. 

In follow-up experiments, Lockery’s team was able to determine the specific neurons affected by Anandamide. Backing up the 2005 research in Science Signaling, they found that the affected neurons became more sensitive to the smell of higher-quality food and less sensitive to that of lower-quality food. 

According to these papers, the munchies are essentially the result of cannabinoids interacting with your endocannabinoid system. It’s a survival impulse that makes you crave high-fat and high-sugar-content foods, and that makes them taste and smell better than they would otherwise. Combine that with the lowered inhibitions that come with a cannabis high, and the table is set for a THC-fueled feast. 

“It’s a really beautiful example of what the endocannabinoid system was probably for at the beginning,” Lockery said.


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