Coined after the French word ‘calorique’ or heat substance, the ‘calorie’ (cal) is defined as the energy necessary to raise the temperature of 1 kg of water from 14.5 °C to 15.5 °C. The Calorie with a capital C, used in describing the energy content of foods, is actually a kilocalorie.
Low calorie is defined as no more than 40 calories per serving and no more than 40 calories per 100 g of food. The proposed definition of calorie-free is less than five calorie for each serving.
Although the kilocalorie is till widely used in the United States, the joule is actually the designated SI unit of energy. Conversion between calories and joules can easily be accomplished using the following equation:
1 calorie = 4.184 joules
What is the definition of calorie?