I wouldn't recommend it for various reasons. Popcorn is made from corn (a grain) and grains have a lot of carbs. According to the USDA, air-popped popcorn has 2.9 grams of protein, 18.7 grams of carbs and 3.6 grams of dietary fiber per serving. That doesn't mean you can't, occasionally, have some popcorn. But make sure it remains an exception and not a daily snack.