To try to snack in a more healthy manner, I've been keeping the house stocked with apples. When I start checking the refrigerator for a little something, I consciously say "Eat an apple, then see how you feel." It's kept me from eating an additional meal's worth of food for a "snack" on more than one occasion.
I've looked into food allergies since being diagnosed with fibromyalgia. I believe I have a sensitivity to wheat; I feel much better when I avoid bread & cereal products, and have lost a bit of weight as well. It's amazing to find common allergens as (seemingly unnecessary) additives in so many foods. A friend's sister has three children with gluten and dairy issues, and has to pack a cooler of food to go ANYWHERE.