Calculate the calories in a serving of food that has 8 grams of protein, 5 grams of fat, and 12 grams of carbohydrate. Which nutrient provides the most percent calories of this food?
The correct answer and explanation is :
To calculate the total calories in the food serving:
- Protein: 8 grams × 4 kcal/g = 32 calories
- Fat: 5 grams × 9 kcal/g = 45 calories
- Carbohydrate: 12 grams × 4 kcal/g = 48 calories
Total Calories = 32 + 45 + 48 = 125 calories
Now, calculate the percentage of total calories from each nutrient:
- Protein: (32 / 125) × 100 = 25.6%
- Fat: (45 / 125) × 100 = 36%
- Carbohydrate: (48 / 125) × 100 = 38.4%
✅ Answer: Carbohydrate provides the most percent calories of this food (38.4%).
🔍 Explanation (approx. 300 words):
Understanding how calories are derived from macronutrients is key to evaluating the nutritional composition of a food item. The three main macronutrients—protein, fat, and carbohydrates—each provide energy, but in different amounts per gram:
- Protein: 4 kilocalories per gram
- Carbohydrates: 4 kilocalories per gram
- Fat: 9 kilocalories per gram
To find the total calories in a serving, we multiply the grams of each nutrient by its respective caloric value and sum the results. In this case, the food contains 8g of protein (32 kcal), 5g of fat (45 kcal), and 12g of carbohydrates (48 kcal), yielding a total of 125 kcal.
Next, we determine what percentage of the total calories each nutrient contributes. This is calculated by dividing the calories from each nutrient by the total calories and multiplying by 100. The nutrient with the highest percentage of total calories is the one that contributes the most energy relative to the others.
From our calculations:
- Carbohydrates contribute 38.4%
- Fat contributes 36%
- Protein contributes 25.6%
Although fat has the highest energy per gram, in this case, the greater quantity of carbohydrates in the serving results in carbohydrates contributing the most calories overall. This insight helps consumers make informed dietary choices based on their health goals, such as managing blood sugar, controlling weight, or balancing macronutrients.