Scientists have discovered a new brain circuit that causes marijuana users to get insatiably hungry, commonly known as “the munchies.” In a study of mice, researchers found the hunger is triggered in part by brain cells that usually turn down appetite.

Marijuana causes these brain circuits to switch from signaling “don’t eat” to “eat,” USA Today reports. The findings appear in Nature.

The Yale University researchers gave mice a synthetic version of one of the active ingredients in marijuana, and were surprised to find it activated brain cells called POMC neurons, which usually repress the urge to eat. Mice given the drug ate three to four times their normal amount of food.

“By observing how the appetite center of the brain responds to marijuana, we were able to see what drives the hunger brought about by cannabis and how that same mechanism that normally turns off feeding becomes a driver of eating,” study author Tamas Horvath said in a news release. “It’s like pressing a car’s brakes and accelerating instead. 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 new findings could be used to help develop treatments for cancer patients, who often lose their appetite during treatment, Horvath noted.