Egg whites can be substituted for whole eggs, saving the health-conscious dieter a substantial amount of calories, fat and cholesterol. Egg whites are very high in the protein albumen, and contain no fat.
As per the USDA's Nutrient Database, an egg white contains 17 calories, 3 g of which consist of protein. One egg white only contains 0.06 g of fat and contains 0 mg of cholesterol.
Whole eggs consist of about 66 percent albumen egg white according to the American Egg Board's website. Also according to the American Egg Board, egg whites contain more than half the protein, most of the niacin, riboflavin, magnesium, potassium and sodium of the egg, and none of the egg's fat.
Egg whites may be substituted for whole eggs in most recipes using two egg whites in place of one whole egg. By comparison, the substituted egg whites would provide 34 Calories, 7 g of protein, and zero g of fat, as compared to the 78 Calories, 6 g of protein, and 5 g of fat in a whole egg.