Editing Calorie (section)

==Usage==
===Nutrition===
In the [[United States]] and Canada, in a nutritional context, the "large" unit is used almost exclusively.<ref>{{Cite journal |last=Nutrition |first=Center for Food Safety and Applied |date=7 March 2022 |title=Changes to the Nutrition Facts Label |url=https://www.fda.gov/food/food-labeling-nutrition/changes-nutrition-facts-label |journal=FDA |language=en}}</ref><ref>{{Cite web |last= |title=Elements within the Nutrition Facts table |url=https://inspection.canada.ca/en/food-labels/labelling/industry/nutrition-labelling/elements-within-nutrition-facts-table#s2c1 |url-status=live |archive-url=http://web.archive.org/web/20240625213453/https://inspection.canada.ca/en/food-labels/labelling/industry/nutrition-labelling/elements-within-nutrition-facts-table |archive-date=2024-06-25 |access-date=2025-04-23 |website=[[Canadian Food Inspection Agency]] |language=en}}</ref> It is generally written "calorie" with lowercase "c" and symbol "cal", even in government publications.<ref name=FDA2019/><ref name=NHS2019/> The SI unit [[kilojoule]] (kJ) may be used instead, in legal or scientific contexts.<ref name=ukmetric2012/><ref name=NPL2016/> Most American nutritionists prefer the unit kilocalorie to the unit kilojoules, whereas most physiologists prefer to use kilojoules. In the majority of other countries, nutritionists prefer the kilojoule to the kilocalorie.<ref name=patt2017/>

In the [[European Union]], on [[nutrition facts label]]s, energy is expressed in both kilojoules and kilocalories, abbreviated as "kJ" and "kcal" respectively.<ref>{{Cite web |title=EU Regulation No 1169/2011 of the European Parliament and of the Council of 25 October 2011 on the provision of food information to consumers |url=https://eur-lex.europa.eu/eli/reg/2011/1169/oj#d1e2548-18-1 |access-date=18 April 2022 |website=EUR-Lex |language=en}}</ref>

In [[China]], only kilojoules are given.<ref>{{Cite web |last=USDA |date=2013 |title=China, General Rules for Nutrition Labeling of Prepackaged Foods |url=https://apps.fas.usda.gov/newgainapi/api/report/downloadreportbyfilename?filename=General%20Rules%20for%20Nutrition%20Labeling%20of%20Prepackaged%20Foods%20_Beijing_China%20-%20Peoples%20Republic%20of_1-9-2013.pdf |access-date=18 April 2022}}</ref>

===Food energy===
The unit is most commonly used to express [[food energy]], namely the [[specific energy]] (energy per mass) of metabolizing different types of food.  For example, [[fat]] (triglyceride lipids) contains 9&nbsp;kilocalories per gram (kcal/g), while [[carbohydrate]]s (sugar and starch) and [[protein (nutrient)|protein]] contain approximately 4&nbsp;kcal/g.<ref name=SciAm/> Alcohol in food contains 7&nbsp;kcal/g.<ref>{{Cite web|url=http://www.nutristrategy.com/nutrition/calories.htm|title=Calories - Fat, Protein, Carbohydrates, Alcohol. Calories per gram|website=Nutristrategy }}</ref> The "large" unit is also used to express recommended nutritional intake or consumption, as in "calories per day".

[[Dieting]] is the practice of [[eating]] food in a regulated way to decrease, maintain, or increase [[body weight]], or to prevent and treat diseases such as [[diabetes]] and [[obesity]]. As weight loss depends on reducing caloric intake, [[List of diets|different kinds]] of [[Calorie restriction|calorie-reduced]] diets have been shown to be generally effective.<ref name="Strychar">{{Cite journal |last=Strychar |first=I. |date=3 January 2006 |title=Diet in the management of weight loss |journal=Canadian Medical Association Journal |volume=174 |issue=1 |pages=56–63 |doi=10.1503/cmaj.045037 |issn=0820-3946 |pmc=1319349 |pmid=16389240}}</ref>

===Chemistry and physics===
In other scientific contexts, the term "calorie" and the symbol "cal" almost always refers to the small unit; the "large" unit being generally called "kilocalorie" with symbol "kcal". It is mostly used to express the amount of energy released in a [[chemical reaction]] or [[Phase transition|phase change]], typically per [[mole (unit)|mole]] of substance, as in [[kilocalorie per mole|kilocalories per mole]].<ref name=rappo2007/> It is also occasionally used to specify other energy quantities that relate to reaction energy, such as [[bond energy|enthalpy of formation]] and the size of [[activation energy|activation barrier]]s.<ref name=bhag2002/> However, it is increasingly being superseded by the SI unit, the joule (J); and metric multiples thereof, such as the kilojoule (kJ).{{citation needed|date=March 2023}}

The lingering use in chemistry is largely because the energy released by a reaction in [[aqueous solution]], expressed in kilocalories per mole of reagent, is numerically close to the concentration of the reagent in moles per [[liter]] multiplied by the change in the temperature of the solution in kelvins or degrees Celsius. However, this estimate assumes that the [[volumetric heat capacity]] of the solution is 1&nbsp;kcal/([[litre|L]]⋅[[kelvin|K]]), which is not exact even for pure water.{{citation needed|date=March 2023}}