My advice regarding eating stuff you know you shouldn't is something I picked up from Deepak Chopra that really works.
When you go to eat something naughty, don't do anything else. Turn off the TV, radio etc. Sit down and eat. Eat every mouthful consciously. That is, put down your knife and fork, or choccy bar, after every bite, and really get into the experience of what you're eating. Chew it completely and savour it. This way of eating may wake you up enough to realise when you have to stop. All cravings, etc come from a lack of consciousness. From being fast asleep. As soon as we "wake up" we find ourselves in a more powerful and controllable position, a centered and balanced state. From here we often find we don't want or need the comfort of that foodstuff. We find we already have everything we need, and everything is fine just as it is. This powerful place is where true healing begins and ends.