Cannabis has a well-known range of side effects: a feeling of being chilled out, prone to giggling, more intense colors, time feeling like it slowed down and, of course, the famous “munchies”.

A new paper, presented at a recent Florida gathering of the Society for the Study of Ingestive Behavior, takes an inventive look at the munchies. In a brand new animal study, yet to be peer-reviewed, they find out that the way cannabis exposure affects appetite is far more complex than many previously thought.

The researchers, from Washington State University (WSU), point out that despite the commonality of the hunger pangs people get post-puff, it’s not entirely clear why they occur.

“We all know cannabis use affects appetite, but until recently we've actually understood very little about how or why,” co-author Dr Jon Davis, a researcher in the Department of Integrative Physiology and Neurosciences at WSU, said in a statement. “By studying exposure to cannabis plant matter, the most widely consumed form, we’re finding genetic and physiological events in the body that allow cannabis to turn eating behavior on or off.”

In this case, Davis is referring to the administration of cannabis to lab rats through a bespoke vapor generation tool. This permitted the team to give very specific doses of the drug to rats’ dinners, which allowed them to match these up with certain types of behavior.

Yes, rats aren’t immediately comparable to humans, but they make for an adequate analogue in certain cases. As it so happens, even the briefest exposure to cannabis vapor provoked rats that had already eaten to seek out another meal – one that was smaller than the main course, so to speak.

This suggests that, much like humans, rats get the munchies too, but why?

When humans get hungry, it’s often (obviously) because our stomach is fairly vacant of any foodstuffs (or liquids). Using a hormone named ghrelin, it beams a message to our brain, which then tells us to shove some food into our faces.

It’s been previously acknowledged to be released more when we use cannabis products, too, and indeed, after a short delay, rats experienced a ghrelin surge after getting a little high. The team used another drug to prevent the hormone spike and found that, as expected, this negated the rats’ munchies.

The cannabis appears to alter the genetic activity of the requisite brain cells in the hypothalamus, but it’s unclear why this happens.

Now, this is all very interesting, but here's the kicker: It’s not yet known why cannabis causes a ghrelin surge. In fact, it’s uncertain what mechanism, or mechanisms, are responsible for the renewed appetite trigger, and what specifically in the cannabis kickstarts them.

Tetrahydrocannabinol, better known as THC, is the brain-altering chemical that’s most responsible for the psychological effects of cannabis. It’s been blamed for the munchies effect too, but exactly why it might do this remains elusive.

One school of thought is that parts of the brain that tell us how full we are when eating are switched off when we’re high, so we consume more. Perhaps, per CNN, it’s more down to the fact that we receive more of the “reward” hormone, dopamine, when we’re high, which switches off our inhibitions.

Other research suggests that it binds to receptors in the olfactory centers of our brain. This boosts our sensitivity to smell, which makes food aromas seem more enticing and intense.

Is the THC also what’s causing the ghrelin surge? If so, how? Right now, we can’t really be sure – so consider the case of the munchies open for the time being.