One more interesting tidbit from Rethinking Thin is what one of the dieters in the book says. He is Jewish and he made a decision to eat Kosher, based on his religion. He immediately removed all foods from his diet that were not Kosher and knew that he would not eat them again. When he attends parties or other food events and he isn't certain that the food is Kosher he simply does not eat it. He said that he has absolutely no problem avoiding foods that don't fit into this diet. He knows he will simply not eat them.
But he does not have the same will, if that's what it is, when it comes to foods that his weight-loss diet says are bad for him. He slips. He has trouble not eating his favorites, or satisfying his sweet tooth when it beats down his defenses. He wonders if getting thin is less important to him than his religion.
So it appears that my hypothesis is probably correct. Following a diet for health reasons, whatever the diet, is damnably difficult. Yet choosing not to eat foods because we are morally opposed to eating them is an entirely different ball game.
Oh, and an aside about this man wondering if he just "doesn't care enough" about getting thin. There is no statistical difference in the psychological makeup of fat and thin persons. In fact, both fat and thin persons have similar cravings. And resolving childhood issues does not make the fat go away.