to eat when they're not hungry
Before you start emailing death threats, let me explain. When my wife or I cook a meal, we let our children take as much as they want. Our rule is they must eat what they take. This came about because of the wholesale wasting of food at our house. They can have seconds or thirds, as much as they can consume. If one of them starts to get more than we think they can handle, we remind them of the rule. If they decide to continue on and load down their plate, that's what they have to eat. If they get stubborn about it, we refrigerate the plate, and they get served only that food until it is consumed. Now that they have realized that they can get seconds or thirds, they take small portions. My youngest daughter lost some of her chubbiness, since she realized that she was full after eating a normal meal.