Popcorn is a whole grain food which is low in calories and also a good source of fiber. 3 cups of popcorn counts as one of your three recommended servings of whole grains per day. Air popped popcorn is only 30 calories per serving, provided you hold the butter.
Substitute potato chips with popcorn as a healthier snack. Just make sure you steer clear of popcorn drizzled heavily with butter, cheese or caramel because those calories can add up fast. Also remember to choose brands that are low sodium.