Air-Popped Popcorn:

Popcorn is a great flat-belly snack as long as you choose the air-popped version—you can eat a 3-cup portion for only 100 calories! Not only that, but popcorn is also a whole grain, and studies show that people who eat whole grains have less belly fat than those who eat refined grains.

Because of its low calorie content, low energy density, high fiber content and increased satiety, eating popcorn may help you eat fewer calories and lose weight. However, moderation is key. Even though it is much more filling than many other snack foods, it can still be fattening if you eat too much of it.