I privately think it has something to do with a broken glucose metabolism. basically, your cells are out of energy. so you have cravings for all kinds of stuff that ramps up your basic metabolic rate.

or you crave food. if you eat food, like with sugar and carbohydrates, your blood sugar is ramped up, if blood sugar has a spike, insulin gets released, and you need this insukline to push the glucose out of your blood in your cells, so you end up having energy. and that makes you happy.

so thats what i believe

alcohol gives you energy by the way, like. in the individal cell.

so the instant gratification is your cells having energy.