I do generally restrict snack to one serving, for that reason. snacks are usually quite yummy and they fall between meals usually after a ton of play, so kiddos are quite hungry, they glom it up and always want more. that's when I look and them and say: "lunch will be soon enough, clear your spot and go back to play", although I do enjoy snack most days myself and feel it is nice to have that extra bit of healthy food, I also don't believe it is 100% neccesary and can sometimes hinder the childs hunger just enough to know, "if i don't eat lunch, I can hold out for pm snack" uh uh! not here, I am required to provide the silly snack am and pm, so I do..if I had my way, with my lite eaters? I wouldn't offer snacks at all, ensuring they eat a quality lunch. I do however, give each child what I know they can handle and still eat lunch, not to mention, I don't require a large consumption of lunch but each child must take part in lunch, one bite of each item is enough (not satisfactory to me) but enough to be done. If they want a treat after lunch or seconds of a specific item, they must clear their plate completely. Maybe your snacks are too large, or too close to lunch time? can you move them a little, or offer the kids less?