system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do you get so hungry from smoking weed?
gpt
I wrote a paper on this for a class....

THC (the active ingredient in marijuana) binds to the cannabinoid type-1 (CB1) receptors in the olfactory bulb (sense of smell) of animal brains and stimulates them, which increases the animal’s ability to smell food. Scent and taste are very closely related, with as much as 80% of flavor sensation coming from the smell of food as opposed to the taste. 

THC also acts on the nucleus accumbens (part of the pleasure and reward system) of the brain, increasing the release of dopamine (a "pleasure chemical") that accompanies eating, causing an increase in pleasure that goes along with it.

Finally, another effect of THC's action on the brain is that it mimics the sensation of being food-deprived, which is believed to be the underlying cause of both the above effects.

So tl;dr - it makes your brain think you're starving so food smells stronger and tastes better and you feel more pleasure (more rewarded) for eating.