Powdered sugar is granulated sugar, ground into a fine powder with a small amount of cornstarch added to prevent the sugar from clumping. Powdered sugar contains no vitamins or minerals, however, it does contain high levels of calories per measure.
According to the U.S. Department of Agriculture nutrient database, there are 467 calories within a 1-cup measure of unsifted powdered sugar. Of that amount, carbohydrates make up the entire amount. Proteins and fats contribute no calories to powdered sugar.
Total Caloric Intake
A 1-cup measure of powdered sugar can deliver nearly 25 percent of the recommended daily caloric intake for the average adult. A 2000 calorie per day diet is used to calculate this percentage.
The same quantity of powdered sugar weighs 120 g, states the USDA, and consists of exactly 120 g of carbohydrates. There are no proteins, fats, other nutrients or water in powdered sugar.