Which of the following statements is true about calories in the context of energy in food?

• A. A calorie is a unit of energy; on Nutrition Facts labels, “Calories” refers to kilocalories (kcal).
• B. A calorie measures the volume of food, so larger foods always have more calories regardless of macronutrients.
• C. A calorie is a unit of protein; higher-protein foods always have more calories than higher-fat foods.
• D. A calorie is the same as a vitamin, meaning it provides energy without being metabolized.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the definition of a calorie in nutrition. A calorie is a unit of energy, specifically the amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius.
2. Step 2: Recognize that on Nutrition Facts labels, the term “Calories” actually refers to kilocalories (kcal), which is 1000 calories in the scientific sense. This is the standard unit used to express the energy content of food.
3. Step 3: Evaluate the incorrect statements by understanding that calories do not measure the volume of food; rather, they measure the energy content, which depends on the macronutrient composition (carbohydrates, proteins, fats) rather than size alone.
4. Step 4: Clarify that a calorie is not a unit of protein, and higher-protein foods do not necessarily have more calories than higher-fat foods because fats provide more calories per gram (9 kcal/g) compared to proteins (4 kcal/g).
5. Step 5: Understand that calories are not vitamins; vitamins are micronutrients that do not provide energy themselves but assist in metabolic processes, whereas calories represent the energy available from macronutrients.