In nutrition and food energy labeling, what is the difference between a calorie (cal) and a Calorie (Cal) (also written as kilocalorie, kcal)?

• A. A calorie (cal) measures protein energy only, while a Calorie (Cal) measures carbohydrate and fat energy only.
• B. A calorie (cal) is used for liquids and a Calorie (Cal) is used for solid foods.
• C. 1 calorie (cal) equals 1,000 Calories (Cal); the lowercase unit is larger.
• D. 1 Calorie (Cal) equals 1,000 calories (cal); Cal and kcal are the same unit.

Answer: (D)

Verified step by step guidance

1. Understand that in nutrition, the term 'calorie' can refer to two different units: the small calorie (cal) and the large Calorie (Cal), which is also called a kilocalorie (kcal).
2. Recognize that 1 Calorie (Cal) or kilocalorie (kcal) is the amount of energy needed to raise the temperature of 1 kilogram of water by 1 degree Celsius, whereas 1 calorie (cal) is the energy needed to raise 1 gram of water by 1 degree Celsius.
3. Note that the relationship between these units is: \$1\ \text{Calorie (Cal)} = 1\ \text{kcal} = 1000\ \text{calories (cal)}$.
4. Understand that food energy labels typically use the large Calorie (Cal) or kilocalorie (kcal) to express the energy content of foods, not the small calorie (cal).
5. Conclude that the difference is purely a matter of scale and notation, not related to the type of macronutrient or the physical state of the food.