calorie

Meaning of calorie: On nutrition labels, the Calorie is actually a kilocalorie, one thousand times the small calorie used as the strict scientific unit of energy.

Definition of calorie

A calorie is a unit used to measure energy, originally defined as the amount of heat needed to raise the temperature of one gram of water by one degree Celsius. In everyday nutrition, the word calorie is used loosely to describe the energy content of food and the energy the body uses to function.

The Calorie referred to on nutrition labels and in common dietary use, sometimes written with a capital C, is technically a kilocalorie, equal to one thousand of the small calories used in strict scientific measurement. The body uses this energy for basic functions such as breathing and circulation, referred to as resting energy needs, as well as for physical activity.

Energy needs can increase during illness, when the body may require additional calories to support processes such as fighting infection or healing, and calorie needs are also considered alongside the balance of nutrients, such as protein, fat, and carbohydrate, that make up a person's overall diet.