Years ago I worked in an office where a group of people had a weight-losing contest. They all contributed 20 bucks, and whoever lost the most weight after six months got all the money. There were about forty people in it, so the prize was pretty good.
Guy I worked with; Jim, joined the contest. He was just a normal sized guy, not fat at all. He waited until the last month or so, dropped forty pounds, took all the money, then put the weight back on. He looked like hell at the weigh-in, but he was $800 richer. Two years in a row he did this. The fatties were mad, so the next year they made some complicated scheme where you had to weigh in every two weeks or something. Jim still won. That was the last year of the contest.
He told me he just quit eating so much. That was his secret.