You will find that carbohydrate-rich foods generally take up the most space on your plate. Present in breads, cereals, vegetables, fruits and sweetened beverages, carbohydrates are the major contributors of energy in your diet. This matches the 2010 Dietary Guidelines for Americans, which recommends that you get 45 to 65 percent of your total daily calories from carbohydrates. The rest of the calories in your diet come from fats and proteins. To calculate the percentage of calories from carbohydrates, you need to know both your total calorie intake as well as calories coming from carbohydrates.
Note the total calories and grams of carbohydrates present in foods you eat from the nutrition facts labels. Make sure that you record values that reflect the actual serving size you consume, because your serving size may differ from that recommended on the food label. Repeat this exercise throughout the day as you eat your meals and snacks.
Use the USDA National Nutrient Database to find total calories and grams of carbohydrates present in the serving size of foods such as fresh fruits and vegetables that do not have nutrition facts labels.
Add the total number of calories from all foods that you ate during the day. This figure is the sum total of all calories you obtained from carbohydrates, fats and proteins. Take for example a 2,300-calorie diet.
Add the amount of carbohydrates present in each food recorded in steps 1 and 2 to determine the quantity of carbohydrates consumed throughout the day.
Multiply the total number of carbohydrates obtained in the previous step by 4 to calculate the number of calories from carbohydrates, because carbohydrates provide 4 calories per gram. For example, if you consumed 295 grams of carbohydrates during the day, then calculate calories from carbohydrates like this: 295 X 4 = 1,180 calories.
Calculate percent calories from carbohydrates by dividing calories from carbohydrates by the total calorie intake and multiplying the answer by 100. This would be: 1,180/ 2,300 X 100 = 51 percent calories from carbohydrates.
- You can follow the same steps to determine calories from carbohydrates for each meal instead of the whole day.
As a scientist and educator, Sukhsatej Batra has been writing instructional material, scientific papers and technical documents since 2001. She has a diverse scientific background, having worked in the fields of nutrition, molecular biology and biochemistry. Batra holds a PhD in foods and nutrition, and a certificate in professional technical communication.