There was a great episode of Horizon titled Eat, Fast And Live Longer which tackled the benefits of fasting. Even a very reasonable fasting routine seemed to have a non-trivial positive effect on the show's host. It was convincing enough that I gave it a shot, and though I haven't been able to stick with it (or an exercise routine, for that matter), I felt significantly better in the ~week following even a one day fast.

One of the things suggested by a researcher in the episode, is to make your "cheat day" the day following a fast. Tell yourself that you can eat anything you want, because (and this was certainly my experience) even if you intend to binge heavily, you most likely will not. You will, however, still feel incredibly satisfied after devouring that bag of chips, or splurging on the cheesecake after dinner. I can't remember the exact number, but the researcher mentioned that during this routine, the subjects would only eat around 10% more than their recommended daily caloric intake.