If you have the munchies, try the five-minute rule. Tell yourself you can have a snack after you do something else for five minutes. If it goes well, you may be able to stretch it into 10 or 20 minutes, or distract yourself entirely!

I use a similar trick to see if I can recognize satiety. After I eat a reasonable amount, I interrupt my meal. I actually get up and go to the bathroom. Usually when I come back, that raging hunger is dimmed and often gone entirely. It really works!