What Causes the Munchies?

Scientists have finally begun to understand why smoking pot leads to so many late night trips to Taco Bell.

The main culprit for the munchies is a brain pathway known as the endogenous cannabinoid system, said Harriet de Wit, a psychiatry professor at the University of Chicago. This system, which involves naturally occurring brain chemicals that resemble the active ingredients in marijuana, affects both the body's stress levels and the desire for tasty food, she told Life's Little Mysteries.

When someone smokes pot, the chemicals in the drug combine with the brain's natural chemicals and push this system into overdrive.

"It's been anecdotal lore that people reported for years, and there were some studies in the '70s, but recently there have been more clinical studies that have shown that both marijuana the plant, and THC the chemical, increase caloric intake," de Wit said. "It also seems to trigger a preference for high palatability and high fat. Snack foods."

The link between the endogenous cannabinoid system and appetite has already sparked a new wave of research into the munchies, de Wit said. In fact, she said, pharmaceutical companies are researching both marijuana-like drugs intended to jump-start the appetite of chemotherapy patients and HIV sufferers, and diet drugs that would suppress appetite by interrupting the very system that pot enhances.