Kilocalorie (kcal)

Definition

The kilocalorie (kcal) is a unit of energy equal to 1,000 calories. It is not an SI unit, but it is widely used in nutrition to quantify energy in food. The exact definition states that 1 kcal is the amount of energy required to raise the temperature of 1 kg of water by 1°C at 1 atm pressure.

History

The concept of the calorie was introduced in the early 19th century by Nicolas Clément. In 1925, the term "kilocalorie" was formalized to distinguish it from the smaller calorie. It became widely adopted in nutritional science after World War II.

Uses

Kilocalories are commonly used in nutrition labeling to indicate the energy content of food. They are also used in diet planning and exercise science to measure energy expenditure. Many countries, including the United States and Canada, use kilocalories for dietary guidelines.

Conversions

• 1 kcal = 4.184 kilojoules (kJ)
• 1 kcal = 1,000 calories (cal)

Fun Facts

• A common misconception is that "calorie" and "kilocalorie" are interchangeable; they are, in fact, different units.
• The term "calorie" originates from the Latin word "calor," meaning heat.