kilókcal

Kilocalorie, abbreviated kcal or Cal, is a unit of energy widely used in nutrition to express the energy value of foods and the body's energy requirements. It is commonly referred to as a "calorie" in everyday speech, though scientifically the term calorie refers to a smaller unit.

The kilocalorie is defined as the amount of energy required to raise the temperature of 1 kilogram of water by 1 degree Celsius at standard pressure. One kilocalorie equals 4184 joules.

In the context of human nutrition, the energy content of foods is measured in kilocalories. Food labels usually indicate energy per serving, per 100 grams, and often per day, calculated using the Atwater system.

The Atwater factors assign approximately 4 kcal per gram for protein, 4 for available carbohydrate, 9 for fat, and about 7 for ethanol. Actual metabolizable energy can vary with the food matrix, fiber content, and individual digestion, leading to small differences from the theoretical values.

The term "Calorie" with a capital C on nutrition labels corresponds to one kilocalorie. People often colloquially use "calorie" to mean kilocalorie, which can cause confusion with the smaller gram-calorie used in physics (1 cal = 4.184 J).

Kilocalories are used to gauge energy balance in weight management, with total daily energy expenditure comprising basal metabolic rate, thermic effect of food, and physical activity. They are also used in dietary planning and public health guidelines.