Every person at the table should eat one spoonful of each food at the meal. And no dessert unless the main meal is eaten completely. When they are little, you know approximately how much they are likely to eat, and as they grow and take over that decision, they are much less likely to waste food or overeat if you have been teaching good behaviors from the beginning. This does not mean STUFF them! It does mean be responsible in everything you do, even in your/their use of food.