1) Keep your snack around 200 calories (which believe it or not is not as hard as it would seem. There are all of those teeny, tiny portion 90-calorie pack snack items out there. Think of it this way-you can have two packs now.)
2) Make sure your snack has at least 3 grams of fiber: Fiber gets digested slowly and also keeps your energy up instead of making you have a crash at your desk. It also soaks up water and expands in your stomach to make you feel full.
3) Make sure your snack has at least 5 grams of protein: Protein releases hormones into your body that keeps you satisfied (kinda like Snickers used to claim in it's commercials in the '80s).
4) Make sure your snack has no more than 12 grams of fat: Let's just say "because". I can't preach about calories from fat and jazz that I can't, in good conscience, say I understand.
*These are backed up by registered dieticians Bethany Thayer and Elisa Zied as well as the U.S. Department of Agriculture.