Which statement correctly defines a kilocalorie (kcal) and its relation to dietary energy?

• A. A kilocalorie is the energy required to raise the temperature of 1 liter of water by 1°C.
• B. A kilocalorie is the energy required to raise the temperature of 1 kilogram of water by 1°C.
• C. A kilocalorie is the amount of energy required to raise the temperature of 1 kilogram of water by 1°C.
• D. A kilocalorie is the energy contained in one gram of fat.

Answer: (C)

A kilocalorie is a unit of energy used in nutrition, defined as the amount of energy required to raise the temperature of 1 kilogram of water by 1°C under standard conditions. This ties dietary energy to a concrete physical property of water and equals 1,000 small calories. Using 1 kilogram of water keeps the definition precise and independent of volume, since density can vary slightly with conditions. The idea that dietary energy comes from the energy in foods is what nutrition labels express in kilocalories (Calories). The statement that matches this standard definition—raising 1 kilogram of water by 1°C—best captures what a kilocalorie represents.