Protein! I think if you eat a meal without protein, you leave yourself open to the munchies very soon after. So maybe try incorporating some lean protein with your meals to fill you up. A protein snack is very satisfying if you're still hungry - a hard boiled egg, tin of sardines, a few slices of quorn on ryvita.
It's tempting to reach for something sweet when you get the nibbles, but I've found that protein hits the spot much quicker, and that sweeter treats make me hungrier in the long run.