You might want to consider substituting another kind of cheese for American. I suggest this for two reasons: 1- If you have to cut it, rather than having it presliced, you'll be more mindful of how much you are eating it. 2- American cheese has more additives than other forms of cheese.

I, also, think the hummus suggestion is good. Keeping other healthy snack foods around might also be helpful- fruit, salsa, guacamole, carrot sticks or baby carrots and nuts.