The munchies are real — at least sometimes and for some people — and science has only begun to understand why.

Given the long shared history cannabis has with humanity, several associations have long endured. One of those connections is marijuana and “the munchies” — the increased appetite attributed to weed consumption.

It’s not a completely unfounded association. Many medical marijuana patients cite cannabis’s uncanny ability to induce appetite as a reason for its therapeutic use, yet many pot smokers will tell you they don’t experience an increased urge to stuff their pie holes at all. As it turns out, the munchies are real — at least sometimes and for some people — and science has only begun to understand why.

What little research surrounding appetite and marijuana seems to point to THC as the cannabinoid responsible for inducing hunger and the activation of the body’s CB1 receptors, which triggers the secretion of hormones that cause “the munchies,” according to a study published in the Journal of Biological Chemistry.

The process, however, is complicated. In a different study conducted by Virginia Commonwealth University researchers, CB1 activation also has the reverse effect: suppressing hunger. One drug designed to mimic this effect, marketed under the name Rimonabant, proved effective in suppressing appetite. But it also induced depression and suicidal thoughts, forcing drugmaker Safosi-Aventis to pull Rimonabant from the market, even after European regulators had initially approved its sale.

A 2011 study published in the American Journal of Epidemiology found cannabis smokers generally did not see an increase in weight due to their pot consumption. In fact, among those surveyed, research found that the rates of obesity were higher among non-cannabis users than those that partake in marijuana. Anecdotally, regular and frequent pot smokers report that while smoking weed does not make them hungry, it does improve the sensation of eating, making food taste and smell better, which increases the overall satisfaction of meals.

The complex mechanisms surrounding the active compounds of the cannabis plant and our bodies are still far from being understood enough to manipulate and isolate for specific, desired effects, as tinkering with marijuana’s hunger effects have shown in the case of Rimonabant.

As the public’s support for the decriminalization of marijuana rises, scientists and researchers will have more access to the plant and increased opportunities to understand the layered, complicated biochemical effects of cannabis and its consumers.