Calorie

A unit of food energy. In nutrition terms, the word calorie is used instead of the more precise scientific term kilocalorie. A kilocalorie represents the amount of energy required to raise the temperature of a liter of water one degree centigrade at sea level. Technically, however, this common usage of the word calorie of food energy is understood to refer to a kilocalorie (and actually represents, therefore, 1000 true calories of energy).

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A unit of heat content or energy. The amount of heat necessary to raise 1 g of water from 14.5–15.5°C (small c.). C. is being replaced by joule, the SI unit equal to 0.239 c.. SEE ALSO: British thermal unit. SYN: calory. [L. calor, heat]

- gram c. SYN: small c..

- kilogram c. (kcal) SYN: large c..

- large c. (Cal, C) the quantity of energy required to raise the temperature of 1 kg of water 1°C (more precisely from 14.5°–15.5°C); it is 1000 times the value of the small c.; used in measurements of the heat production of chemical reactions, including those involved in biology. SYN: kilocalorie, kilogram c..

- mean c. one hundredth of the energy required to raise the temperature of 1 g of water from 0–100°C.

- small c. (cal, c) the quantity of energy required to raise the temperature of 1 g of water 1°C, or from 14.5–15.5°C in the case of normal or standard c.. SYN: gram c..

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cal·o·rie also cal·o·ry 'kal-(ə-)rē n, pl -ries

1 a) the amount of heat required at a pressure of one atmosphere to raise the temperature of one gram of water one degree Celsius that is equal to about 4.19 joules abbr. cal called also gram calorie, small calorie

b) the amount of heat required to raise the temperature of one kilogram of water one degree Celsius that is equal to 1000 gram calories or 3.968 Btu abbr. Cal called also kilocalorie, kilogram calorie, large calorie

2 a) a unit equivalent to the large calorie expressing heat-producing or energy-producing value in food when oxidized in the body

b) an amount of food having an energy-producing value of one large calorie

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n.

a unit of heat equal to the amount of heat required to raise the temperature of 1 gram of water from 14.5°C to 15.5°C (the 15° calorie). One Calorie (also known as the kilocalorie or kilogram calorie) is equal to 1 000 calories; this unit is used to indicate the energy value of foods. Except in this context, the calorie has largely been replaced by the joule (1 calorie = 4.1855 joules).

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cal·o·rie (kalґə-re) [Fr.; L. calor heat] any of several units of heat defined as the amount of heat required to raise the temperature of 1 kilogram of water 1 degree Celsius at a specified temperature. The calorie used in chemistry and biochemistry is equal to exactly 4.184 joules. Symbol cal. NOTE: There was formerly a distinction made between the “small calorie,” defined above, and the “large calorie,” written Calorie with a capital “C” and abbreviated Cal, which was equal to 1000 small calories or one kilocalorie. The use of the large calorie survives only in nutrition, where calorie, now usually written with a small “c,” means kilocalorie when specifying the energy content of foods.