In nutrition, calories (kilocalories, kcal) are used to measure what type of energy in food?

• A. The amount of mechanical energy produced by skeletal muscle contraction
• B. The amount of nuclear energy stored in the atoms of food
• C. The amount of electrical energy generated by ions in body fluids
• D. The amount of energy released as heat when food is metabolized by the body

Answer: (D)

Verified step by step guidance

1. Understand that in nutrition, calories (kilocalories, kcal) measure the energy content of food that the body can use.
2. Recognize that this energy is released during the metabolic processes when the body breaks down macronutrients like carbohydrates, fats, and proteins.
3. Know that this energy is primarily released as heat, which the body uses to maintain temperature and fuel biological functions.
4. Differentiate this from other forms of energy such as mechanical energy (muscle contraction), nuclear energy (atomic level), or electrical energy (ions in body fluids), which are not what calories measure in food.
5. Conclude that calories represent the amount of energy released as heat when food is metabolized by the body.