Marijuana Munchies Are Driven By Heightened Sense of Smell

By Carl Engelking | February 10, 2014 4:01 pm

“The munchies” are one of the well-documented side effects of marijuana, driving many a midnight smoker to compulsive snacking. Now, for the first time, scientists have a complete understanding of why the drug leads to a refrigerator raid – and, they say, their findings could usher in new treatments for eating disorders from obesity to anorexia.

It turns out that the active ingredient in cannabis, tetrahydrocannabinol (THC), ramps up the sense of smell in mice, which in turn increases their drive for food, according to French researchers. Their findings were recently published in the science journal Nature Neuroscience.

Cannabis on the Brain

Scientists already knew that THC binds to a certain kind of receptor, called a cannabinoid receptor, in the brain. This blocks brain signals that tell us not to eat, thus making us hungry. However, smell also plays a key factor in stimulating appetite, and scientists didn’t how fragrance fit into the mix.

Researchers weren’t looking at marijuana specifically. Rather they were curious if cannabinoid receptors played a role in heightening hungry people’s sense of smell. In studies on mice, they found that famished mice ate much more when they were injected with THC than when they weren’t. And hungry mice given THC but whose cannabinoid receptors had been turned off didn’t eat any more than usual.

Mice treated with THC also responded to fainter whiffs of banana and almond oils, signaling a heightened sensitivity to smell. Therefore, the study suggests, Bob Marley tunes aren’t the only thing getting turned up during a smoke session: Cannabis smokers’ sense of smell is heightened, which increases their appetites.

Heady Medication

If the findings hold true in humans, they could yield novel approaches to treating eating disorders, by manipulating the link between smell and appetite in our brains. New obesity treatments could be possible, by interfering with cannabinoid signaling to reduce people’s hunger drive. (The drug company Sanofi-Aventis introduced just such a cannabinoid-blocking drug for obese patients in 2006, according to New Scientist, but it was withdrawn because it sometimes produced severe anxiety and depression.) Conversely, a drug could enhance cannabinoid signaling for people who suffer from appetite loss, such as cancer patients.

Something to think about the next time you catch a whiff of something delicious – your brain’s natural cannabinoids are marching you toward the munchies.

Image credit: ollyy/Shutterstock

  • Bill Skaggs

    Excuse me, but if you’re going to blog about a scientific paper, please give readers *some* way of finding the original publication — if not a reference, at least the journal or the name of one of the authors.

  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    Do the experiment. Eat the pizza and Coke first, then circulate the reefer doobie blunt joint jay spliff. Full bellies still demand a jar of applesauce and a bag of chips. A head cold empirically does not change that.

    Cancer patients shall NOT have access to any Schedule One pharmaceutical. Schedule One controlled substances are reserved for criminality and social compassion only. “You know, this terrible pain is only the kiss of Jesus,” Mother Teresa. One hopes her husband gave her prolonged thorough consideration on her way out.

  • Steve

    Why do we have cannabinoid receptors? Does that mean we’re supposed to be ingesting cannabinoids?

    • http://blogs.discovermagazine.com Longmire

      Yes of course it does.

    • EdgarSG

      In fact, cannabinoid receptors are activated by endogenous molecules called endocannabinoids. So, everybody produces its own cannabinoids.

  • UberPillz

    funny, i tend to notice food smells more when i’m hungry. like after smoking pot. which brings us back to square one.

  • http://blogs.discovermagazine.com Longmire

    I believe there is more to the munchies than just a heightened sense of smell. Cannabis heightens all the senses which means that the mind is working overtime gathering and processing information which causes the brains of those that rarely use theirs to seek fuel and in return tells the conscious mind to eat and then eat some more. It is an over looked fact that the mind uses energy (20% of the total) and when nervous or overly focused it consumes far more. This could be proven by giving “geeked” participants different foods with the same caloric value, with some receiving “brain food” like dark chocolate and others eating white chocolate or ice cream and the results would consistently show that those that consume the brain food would consume less calories than the others showing that its the mind that needs fed not just some reaction to bound receptors. Another way to measure the effect would be to put a group in an environment where their mind is stimulated and the other in a situation that uses little mental activity and then introduce subtle smells the stimulated group would get the “munchies” sooner which should not be the case.

    • EdgarSG

      I fully agree. In humans, such effect could be more complex. Because as you said, cannabinoids enhance sensory perception, for good and for bad. However, It is also true that the human olfactory system is, lets say, understudied. I am sure we will be quite surprised about all the information passing by our nose and influencing our behavior.

  • John

    I get the screaming munchies and I have no sense of smell…zero. My girlfriend can emit the raunchiest gas attack and I can smile right through the gas trap that leaves the hairs in my nose smoking while I go for the ice cream. There’s not much science in my comment, just my personal experience with THC.

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