One cup of plain air-popped popcorn—without butter, salt, or other toppings—contains about 30 calories, according to the U.S.
Three cups of plain popcorn has 93 calories, 3.6 grams of fibre, 3 grams of protein, 18.6 grams of carbohydrates and 1.1 grams of fat. Popcorn also has a low glycemic index, so it can help ...