Brian Wansink is a Cornell researcher who does fantastic work on eating behavior (from food shopping to eating at restaurants, schools and homes). I recommend his book Mindless Eating for some surprises on how people respond to subtle cues.
He has a project aimed at school lunches that can be very cost effective.
I found a nice introduction to his work in an audio interview at Yale. Short, but in two parts - the second focusing on children's lunches in schools:
part 1 (15 minutes)
part 2 (17 minutes)
... a very entertaining speaker ...