system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why weed gives you 'the munchies'

Don't usually smoke the whacky bacci but last night I had a bit and ate a large McDonalds 1/4 pounder meal 2 cheese burgers 9 chicken nuggets and a bowl of cereal when usually I'd be feeling sick after eating the meal on its own!
gpt
Cannabis contains substances known as cannabanoids. There are types that come from plants like cannabis, and types that occur naturally in your brain. The types that are usually in your brain when you don't smoke help regulate hunger: they send signals that tell the brain, "hey, the body needs food!" When your stomach is full of food, cannabanoids are not used by the brain in this way. This is changed when you ingest or inhale cannabanoids from cannabis: the brain thinks these are natural signallers telling it that the body needs food, even if it doesn't.