Calorie

The calorie is a pre-SI metric unit of energy. It was first defined by Nicolas Clément in 1824 as a unit of heat, entering French and English dictionaries between 1841 and 1867. In most fields its use has been replaced by the SI unit of energy, the joule. However, it remains a commonly used unit for energies in the field of chemistry, and in many countries it remains in common use as a unit of food energy.

Definitions of the calorie fall into two classes:

  • The small calorie or gram calorie (symbol: cal) approximates the energy needed to increase the temperature of 1 gram of water by 1 °C at standard atmospheric pressure (101.325 kPa). This is approximately 4.2 joules.
  • The large calorie, kilogram calorie, dietary calorie, nutritionist's calorie or food calorie (symbol: Cal) approximates the energy needed to increase the temperature of 1 kilogram of water by 1 °C. This is exactly 1,000 small calories or approximately 4.2 kilojoules.

The calorie, the kilocalorie and the kilojoule are in common use in nutritional contexts as units of food energy. As used in these contexts the calorie (unprefixed) is based on the kilogram whereas the kilocalorie is based on the gram. That is, the nutritional calorie is the kilogram calorie and the kilocalorie is one thousand gram calories. Thus, in nutrition, the terms calorie and kilocalorie refer to equivalent units.

In an attempt to avoid confusion, the large calorie is sometimes written as Calorie (with a capital C). This convention, however, is not always followed, and not explained to the average person clearly (and is sometimes ambiguous, such as at the beginning of a sentence). Whether the large or small calorie is intended often must be inferred from context. When used in scientific contexts, the term calorie refers to the small calorie; it is often encountered in experimental calorimetry, and commonly used to specify bond and conformational energies in molecular modeling.

Read more about Calorie:  Definitions

Other articles related to "calorie, calories":

Calorie - Definitions
... Accordingly, there have been several definitions of the calorie ... The two perhaps most popular definitions used in older literature are the 15 °C calorie and the thermochemical calorie ... The conversion factors used to convert calories to joules are numerically equivalent to expressions of the specific heat capacity of water in joules per gram or kilogram ...
Medical Research Related To Low-carbohydrate Diets - Specific Research - Nutrition Journal: 2004
... Feinman and Fine, 2004 present an argument refuting the "calorie is a calorie" principle cited by some as an argument against the weight-loss benefits of low-carboh ... The "calorie is a calorie" argument, loosely speaking, states that the laws of thermodynamics imply that calories ingested from any source are burned at the same rate in ... Thus, ironically the dictum that a "calorie is a calorie" violates the second law of thermodynamics, as a matter of principle ...
Human Homeostasis - Energy
... energy balances in the body, energy is often measured in calories, with the definitions of a calorie falling into two classes The small calorie or gram calorie (symbol cal) approximates the energy needed to ... The large calorie, kilogram calorie, dietary calorie or food calorie (symbol Cal) approximates the energy needed to increase the temperature of 1 kilogram of water by 1 °C ... This is exactly 1,000 small calories or about 4.2 kilojoules ...
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... of Sweet'n Low, the saccharin-based zero calorie sweetener sold in pink packets ... Packing produces other table top sweeteners, including NatraTaste, an aspartame-based zero calorie sweetener and NatraTaste Gold, a sucralose-based zero calorie sweetener and Sweet One ... In The Raw natural cane turbinado sugar and Stevia In The Raw all-natural zero calorie stevia-based sweetener ...
Customary Units In The United States - Other Units
... dm3 1 British thermal unit (Btu) ≈ 1055 J 1 calorie (cal) = 4.184 J 1 large calorie (kilocalorie, food calorie) (Cal, kcal) = 4.184 kJ 1 hand = 10.16 cm 1 horsepower ≈ 745.7 W 1 R-value (ft2·°F·h/Btu) ≈ 0.17 ...

Famous quotes containing the word calorie:

    Upscale people are fixated with food simply because they are now able to eat so much of it without getting fat, and the reason they don’t get fat is that they maintain a profligate level of calorie expenditure. The very same people whose evenings begin with melted goat’s cheese ... get up at dawn to run, break for a mid-morning aerobics class, and watch the evening news while racing on a stationary bicycle.
    Barbara Ehrenreich (b. 1941)