My weakness used to be pretzels. I'd pop the lid on one of those big plastic barrel style containers, plop down with a video game and just turn my mind off for a few hours munching away the whole time.
I've thought about what such behavior was doing for me, what benefit did I think I was getting out of it and was it really working? I was truthful with myself and it was suddenly the easiest thing in the world to give up.