I have noticed that when I get all stoned and then eat my dinner, I come down to the point of not being stoned anymore. I think this is because your body releases a form of cannibas in your brain to yourself your hungry and when you eat, your body pumps out the I'm not eating chemicle i.e. the anti-cannibas drug and because of that, it breaks down quicker, thus resulting in my short high. Just my experiance.
So now, when I am done eating, I sit back, relax, and roll a Jay.
Oh yah, it is because your brain naturally releases a version of cannibas in your system is why you get the munchies. The THC triggers the receptors in your brain telling you your hungry and your willing to eat anything as long as its food, even if you normally would not eat it.