Some cravings are physical, stemming from deficiencies of specific nutrients, like sugar, salt or protein. The pituitary gland is involved in the releasing of hormones that will instruct your body what the brain wants.
Other cravings have emotional origins. Dr. Oz says the mamillary bodies control both memory and cravings. Why would these two functions be intertwined? "When you're two years old and you're having a bad time and your mother gives you a fatty food, this part of your brain remembers that. Right next door, when the satiety center says to eat food, the place it draws on its memory from is right next to it. So the mamillary bodies say, 'The last time you had that cream pudding, it took care of your problem.'"
Dr. Oz says the reason you can be stopped dead in your tracks by the smell of cookies baking is because that smell registers right in the middle of your brain. "It bypasses your thought process, it's a reflex," he says. "It mainlines right into the middle of your brain and you don't have any ability to control that."