Calculate Calories: Protein, Fat, and Carbs
Calculate Calories from Fat, Protein, and Carbohydrates
How to determine nutritional values:
- Determine total fat, protein, or carbohydrate content: Divide the specific number of total fat calories by the total number of calories in that serving, as indicated on the nutrient label.
- Determine the percentage of carbohydrates, fats, or proteins in the total amount of food ingested: For example, if you ate 2000 calories and 800 of those calories were from carbohydrates, then 800 divided by 2000 times 100 equals 40%. This means 40% of your daily intake was from carbohydrates, just below the recommended amount of 45-65%.
- Determine total calories in a particular food: Use the number of grams of proteins, fats, and/or carbs. Remember the energy values: Carbs (4cal/g), Proteins (4cal/g), Fats (9cal/g).
Practice Questions
Q1. A food contains 5 grams of protein, 8 grams of fat, and 12 grams of carbohydrate. What percentage of total calories in this food come from each nutrient?
Answer: First, determine total calories; then calculate percentages:
- 5 g protein x 4 calories/g = 20 calories; 20 cal from pro / 140 total cal = 0.143 x 100 = 14.3%
- 8 g fat x 9 calories/g = 72 calories; 72 cal from fat / 140 total cal = 0.515 x 100 = 51.5%
- 12 g carb x 4 calories/g = 48 calories; 48 cal from carb / 140 total cal = 0.343 x 100 = 34.2%
- Total calories = 140; Total percentage = 100%
Q2. How many grams of protein, fat, and carbohydrate can someone eat on a 2,000-calorie diet that provides 30% calories from fat, 20% calories from protein, and 50% of calories from carbohydrate?
Answer: First, determine the calories:
- 30% of 2,000 calories = 0.30 x 2,000 = 600 calories from fat
- 20% of 2,000 calories = 0.20 x 2,000 = 400 calories from pro
- 50% of 2,000 calories = 0.50 × 2,000 = 1,000 calories from carb
Then, determine the grams:
- 600 calories / 9 calories per gram = 67 g fat
- 400 calories / 4 calories per gram = 100 g protein
- 1000 calories / 4 calories per gram = 250 g carb
Q3. If 1200 of the 2300 calories that you consumed for a day come from carbohydrates, what percentage does this represent? How many grams of carbohydrates is this?
Answer: First, determine the percentage: 1200 / 2300 = 0.52 x 100 = approximately 52%.
Next, determine the gram amount: 1200 calories / 4 calories per gram = 300 grams of carbohydrates.
Conversion Formulas
- To convert Grams to calories, MULTIPLY by the energy value.
- To convert Calories to grams, DIVIDE by the energy value.
Examples from a Food Label
1. What percentage of the total calories comes from fat per serving?
43g total fat x 9cal/g = 387 total fat calories; 387 total fat calories / 670 total calories x 100 = 57.8% Total Fat in the serving.
2. a. What percentage of the total calories comes from saturated fat per serving?
17g Saturated fat x 9cal/g = 153 saturated fat calories; 153 saturated fat cals / 670 total cals = 22.8% Saturated Fat in the serving.
3. What percentage of the Daily Value for total fat per serving is contributed by this product?
43g TF / 65g TF x 100 = 66% Daily Value of Total Fat in the product.
4. What percentage of the Daily Value for saturated fat per serving is contributed by this product?
17g SF / 20g SF x 100 = 85% Daily Value of Saturated Fat in the product.
5. What percentage of the Daily Value for sodium per serving is contributed by this product?
1180mg sodium / 2400mg sodium x 100 = 49% Daily Value of sodium in the product.