How We Decide by Jonah Lehrer gives a nice overview of the neuroscience behind how we make decisions, both good and bad. He also wrote a rather good article about self-control for The New Yorker a few years back, in which he concludes that the ability to distract yourself, or to shift your attention away from temptation, is the key to avoiding it. He argues that this ability may be genetic, but that it can also be learned. For issues re: bad romance, I'd recommend Love and Addiction by Stanton Peele. His books and articles about substance abuse are good too, although I think he's a bit too hard on twelve step groups.
Personally, I've found that the best way to avoid drinking too much is to avoid alcohol altogether. Controlling your diet is a bit harder of course, because you can't simply stop eating. What I do is keep track of approximately how many calories I eat during the day, and set a daily limit. I also weigh myself at least once a week to make sure I'm not gaining weight. The downside to this approach is that some people get bored with the whole thing and just give up. I just kept at it until it became a habit, like brushing my teeth or taking out the garbage.