I have somewhat more faith in the body's ability to heal itself if the same bad habits and nutritionally empty foods aren't reverted to. We are designed to go on low calories in the winter, but due to our food supply we have lots of calories. Also, we'd need to be willing to pork up in the fall if we want the weight to come off in the spring.
The French do smoke a lot, which apparently reduces appetite or something. They walk more, and they just generally have smaller portions- which would go with the european fat/satiety claim that I would like to read more about. [snark] And don't they drink wine or the blood of virgins instead of water?[/snark]
There are two other satiety mechanisms- stomach size interacts with the glutamic receptivity, which is why MSG fills you up. Bypass surgery relies on this, but the fat (CCK) reception isn't helped. The other is the Insulin-->seratonin synthesis, which is the pathway that takes 20 minutes. And all of these pathways can be blown out by just overriding them regularly.
I think the trouble with American dieting is that each diet has a safety valve or a cheat. If people follow only one diet, great. But most are following a constellation of different diets with overlapping cheats. Also, processed food is manufactured and marketed with a Darwinian dynamic. The more of something you can sell, the more successful you are and so the drive is only to sell more and not to avoid killing people.