The Calories you see on the nutrition labels of your favorite foods actually represent 1,000 of the calories that are a single unit of heat energy in science. The convention in scientific or academic writing is to capitalize the nutritional Calorie and use lowercase for the single unit of heat, or calorie. To allay confusion, dietitians often use the term kilocalorie, or kcal, to represent Calories. To calculate the percentage of kcals from protein, you need to compare the number of kcals from protein to the total number of kcals.
Step 1
Multiply the grams of protein by four to calculate the number of calories from protein. For example, a food with 10 g of protein contains 40 calories from protein, because 10 times 4 equals 40.
Step 2
Divide the number of calories from protein by the total number of calories. If the food in the above example contains 400 calories, divide 40 by 400, which equals 0.10.
Step 3
Multiply the resulting number by 100 to convert it to a percentage. For example, 0.10 times 100 equals 10, or 10 percent.
Tips and Warnings
- A healthy diet contains 15 to 30 percent of calories from protein each day.
References
- "Nutrition and Diet Therapy Reference Dictionary"; Rosalinda T. Lagua and Virginia Serraon Claudio; 1996
- "Nutrition and Diagnosis-Related Care: Sixth Edition"; Sylvia Escott-Stump; 2008
- "Krause's Food and Nutrition Therapy: 12th Edition"; L. Kathleen Mahan and Sylvia Escott-Stump; 2008
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