In people who have a hard time controlling their eating, their brain circuits remain elevated and activated until all the food is gone. Then the next time you get cued, you do it again. Every time you engage in this cycle you strengthen the neural circuits. The anticipation gets strengthened. It's in part because of ambivalence. Do you ever have an internal dialogue? "Boy, that would taste great. No, I shouldn't have it. I really want that. And I shouldn't do it."
That sort of ambivalence increases the reward value of the food. It increases the anxiety, it increases the arousal, it keeps it in working memory.
--Dr. David Kessler, pediatrician via salon.com
Boy does that ever sound familiar.