Question: the food a man eats has which energy?
Answer: Energy is measured in units of kilocalories (kcal) or kilojoules (kJ). One kilocalorie (1 kcal) is equal to 4.18 kilojoules (4.18 kJ). The amount of energy a food contains per gram is known as its energy density so we can describe fat as more energy dense than protein or carbohydrate.