Ummm this is the complete opposite to what I do. I tend to think…mmm I've got the chocolate, or whatever else is desirable, don't want to waste it, I'll just finish it off and won't buy anymore. Then of course, its on special or I'm hungry when I do the shopping and I buy some more. Rinse repeat. Of course this method works well on food you don't like, so you don't waste them.
I fail regularly at losing weight, so I'll have to try it. Interesting. Maybe a combination of "I've got it, so I don't need more" and "lets see how long I can keep this." Intuitively I think it will be playing with fire, but I can't do any worse than I'm doing so here goes. I did hear of a reformed alcoholic who used to go to the pub every day on the way home and had a single glass of soft drink so he knew he had really licked the habit.