Here is the answer by ChooseYourDiet.com
Brush your teeth. When you feel like snacking, try brushing your teeth. For many people, having fresh minty breath staves off the need to snack. Keep a toothbrush and a travel size tube of toothpaste in your purse or desk drawer. Many times the desire to nibble doesn't come from hunger but from boredom or stress. Instead of paying a visit to the vending machine for chips or candy, hit the bathroom and give your mouth a quick cleansing.