Talk:Calorie/Archive 1

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One Calorie equals 1000 15 °C calories?

This: "one Calorie equals 1000 15 °C calories" means what? Isn't is supposed to be one Calorie equals 1000 calories?Qaz I get it now on second reading of the table... answered my own question.Qaz

Calories in food

I would like to see a discussion of how calories are measured in food. Specifically what kind of lab equipment is used and how it works. Does something like this have a place in wikipedia?

It's burned in a bomb calorimeter. This has been added to the article. -- Curps 10:41, 15 Jan 2005 (UTC)

No, in practice the nutritional composition of food is determined either by chemical analysis (for basic ingredients) or by applying standard tables and taking into account the recipe. The labelled energy of the food is then calculated based on conventional energy densities for the different groups of nutrilitonal substances. This is now described in the article. Bomb calorimeters were only used to agree on the conventional enegry densities, but they are not mentioned in any of the current food labeling regulations. Markus Kuhn 10:58, 4 December 2005 (UTC)

Confusing sentence

I'm not quite sure whether this is accurate:

The energy liberated from the explosion of 1 ton of Trinitrotoluene (TNT) is equal to 1 billion calories (by definition; see the megaton entry).

Firstly, I see from the entry for TNT that it this should be thermochemical calories. Secondly, does that mean that the definition of thermochemical calories is related to the energy released by TNT, or is TNT somehow defined by the energy that is released? If the former, this should be mentioned above where thermochemical calories are first mentioned. If the latter, I fail to understand how this works. I also think we should use a different mass of TNT to avoid the use of billion, which is an ambiguous value (in UK English it traditionally means 10^12, not 10^9 as it is being used here).

I will fix the first and third of these, although feel free to revert me if you disagree. Somebody else really needs to clarify the second.

Three misconceptions

Food calories are not "shortened" from kilocalories

Instead, what we have is two parallel definitions in the development of these units, with a variation in the quantity of water involved. The pound was used in developing the Btu, but for he metric calories, two different choices were made: a gram of water, or a kilogram of water.

This is somewhat similar to the evolution of moles from "gram molecular weight" or "kilogram molecular weight" or "pound molecular weight" to "gram mole" and "kilogram mole" and "pound mole", with the "gram mole" chosen to be the mole of SI.

The two different classes of calorie have been distinguished by calling them the "large calorie" and the "small calorie", or the "kilogram calorie" and the "gram calorie", and because of the way the use of these units evolved, by calling the large calorie a "foot calorie" or "nutrition calorie".

There is no laziness or word-shortening involved here, with people really meaning to say "kilocalorie" but dropping the "kilo".

Nutritionists don't use prefixes with food calories. So as a result, we end up with prefixes onl used with small calories. As a result, we often end up with the confusing, incongruous clashing of the word "calorie" used with the "kcal" abbreviation. Gene Nygaard 14:12, 17 August 2005 (UTC)

I remain sceptical about this view. My scepticism is based on two observations:

• In Europe, food labels consistently use the "kcal" (and kJ) abbreviation. This contradicts the idea that there are two separate "chemistry calories" and "food calories" formally recognized that differ by a factor of 1000. At least from a European point of view, there is only a single calorie (4.185 J), and when people talk about food calories, they just drop the kilo prefix. (In other words, at least in Europe, where the calorie is concerned, nutrition science is just a specialiced branch of chemistry.)
• ISO 31-4 mentions only the 4.185 J calorie (three slightly different versions of it, actually), not any 4.185 kJ calorie.

So there are at least regional variations. I would not be surprised if the context-specific distinction between a gram and a kg based calorie in nutrition and chemistry turns out to be a U.S. specific habit or history, but I'm happy to see historic references to the contrary. Markus Kuhn 16:42, 17 August 2005 (UTC)

The text still does not accurately reflect that in Europe, there is only one single calorie, and food products are consistently (as required by law) labelled in kcal. The "large calorie" that the article describes as being universally used by nutritionist is very much a U.S. specific measurement. The article has at present a strong U.S.-speciftic point of view with regard to the distinction between a "small" and "large" calorie. I propose to restrict the description about nutritionists using a larger kg-based calorie as a practice limited to some countries, most notably the United States. Markus Kuhn 09:40, 26 August 2005 (UTC)

No, that's just part of your misconception. Any of those "laws" dealing with nutrition labeling are recent developments, long after the start of the use of calories. They reflect the fact that since nutritionists did not use the prefixes, whenever a prefix was used with the word calorie, it was the dinky calorie settled on as the standard of the chemists to which it was attached. So since kilocalorie never referred to 1000 large calories, and because chemists and physicists usually are more involved in the politics of the setting of standards, the word "kilocalorie" is a disambiguation of sorts, much like the English use of the word "tonne" even though in French the word "tonne" is also the word which can be used for English short tons or long tons (usually distinguished with an adjective, but don't forget Quebec in this regard--what do you suppose an unidentified tonne was likely to be when used there, say 50 years ago?). The EU, of course, is also interested in uniformity of the unit symbols across language barriers, so this is a reasonable choice to standardize on. The European labels normally do not include the spelled out word kilocalorie, do they? Nor spelled out calorie. Not like the United States, where the word "calorie" is usually used on those labels as a substitute for the quantity being measured, energy.

They were and are called "calories" in the U.K. and other parts of the world, just as they are in the United States and Canada, and the incongruous kcal abbreviation for them is used in the United States and Canada as well as elsewhere.

The problem with your wording was the erroreous claims about the etymology, claiming that the large version was formed by laziness and abridgement of the original word by the dropping of a prefix which was originally there. That isn't the way it happened. Gene Nygaard 11:24, 26 August 2005 (UTC)

May I add to this discussion another authoritative reference to counter Gene's peculiar view of the world: NIST Special Publication 811, Appendix B.8: calorie, which says in footnote 12:

The kilogram calorie or "large calorie" is an obsolete term used for the kilocalorie, which is the calorie used to express the energy content of foods. However, in practice, the prefix "kilo" is usually omitted.

So U.S. food calories are "shortened" from kilocalories. The U.S. government at least says so. I rest my case. Markus Kuhn 11:49, 4 December 2005 (UTC)

Actually, that supports my point, clearly showing that "kilocalorie" is shortened from "kilogram calorie", not "calorie" shortened from "kilocalorie.

Another source; Webster's Third New International Dictionary, 1976 (since additions are put in a separate "Addenda" at the beginning, it really isn't necessary to cite the edition unless the information comes from the addenda; this is from the main part):

cal•o•rie also cal•o•ry [pronunciation omitted] n, pl calories [F calorie, fr. L calor heat + F -le -y—more at CALORIC] : any of several thermal units: a : the amount of heat required at a pressure of one atmosphere to raise the temperature of one gram of water one degree centigrade esp. from 15° to 16°—abbr. cal; called also gram calorie, small calorie b cap (1) : the amount of heat required at a pressure of one atmosphere to raise the temperature of one kilogram of water one degree centigrade : 1000 gram calories or 3.968 Btu—abbr. Cal; called also kilogram calorie, large calorie (2) : a unit expressing a heat-producing or energy-producing value in food that when oxidized in the body is capable of releasing one large calorie of energy (3) : an amount of food (as in a diet) having an energy-producing value of one large calorie c : 1/100 of the amount of heat required to raise the temperature of one gram of water from 0° to 100°C—called also mean calorie

Wish I had the OED too. Gene Nygaard 13:16, 4 December 2005 (UTC)

Calories for food are not capitalized in the U.S.

Contrary to what Markus Kuhn writes now, and various statements made by other editors in the past, there is not a general convention in the United States (nor anywhere else) to write the large calorie as "Calorie" and to use the symbol "Cal" for it.

This is mostly the figment of the imagination of a few chemistry textbook writers, and something not even seen there much any more since most chemistry textbooks have stopped using the small calorie in chemistry. It is not and never was a generally accepted rule. Some chemistry professors still try to teach this in their classes, with little effect. You can throw in an occasional physics professor or textbook author as well, but mostly chemistry.

But chemists don't use large calories, and haven't done so for over half a century at least (and they don't use small calories much any more, either). They forgot to get the people who actually do use the large calorie to play along with their silly game, their attempt to impose a silly rule on the other guy.

Just do an internet search for the use of calorie in the United States, or look at diet books an the like. The word "calorie" is rarely capitalized, unless it starts a sentence or the like. Sure, you will find a small minority of books or internet pages or whatever which do so, but it certainly is not a convention in widespread use.

Of course, the biggest problem is that it is a silly rule in the first place. You cannot tell whether or not the rule is being followed, when the word would be capitalized for other reasons anyway.

I suppose Markus and others are somewhat legitimately confused by United States nutrition labels, where the word calorie is often used not just as a unit of measure, but rather as a synonym for the quantity being measured: food energy. With that substitution, there are generally no unit symbols after the numbers. Especially since the FDA does not encourage the use of joules, and does not even mention them in their labeling regulations, the numbers are usually presented as simply "Calories 130"; there is generally no use of "cal" or Cal" or "kcal" or any other unit symbol on these nutrition labels. It is not generally written in the other order, either. It isn't "130 Calories"; the word "Calorie" starts the line.

Of course, that unit qua quantity is indeed capitalized in that listing of the food energy per serving on most U.S. nutrition labels. But so what? The words "Protein" and "Sodium" and "Sugars" and the like are also capitalized. They are capitalized as the first word of a line in a table. That doesn't tell us anything about whether or not the large calorie is generally capitalized in the United States.

Markus, I imagine you probably have seen that chemistry-textbook rule states somewhere, and imagined it to be confirmed by the capitalization of the listing at the top of a U.S. nutrition label. But it just isn't so.

Just in case you don't have one of those labels handy, and for the benefit of others reading this, an example of these labels can be seen in the Food and Drug Administration web page "How to Understand and Use the Nutrition Facts Label".

Here's the clincher. Guess what else I see on all of those food labels, here in the United States? Look down towards the bottom of the one of these labels. Or look at the examples given for various foods in the bottom half of the FDA page linked to above. Do you see this footnote, which appears with only minor variations on all U.S. nutrition labels?

• "Percent Daily Values are based on a 2,000 calorie diet"

See? The word "calorie" is not capitalized in this sentence on any of the several labels listed on the FDA web page. I have noticed it capitalized on any label, though I wouldn't be greatly surprised if there are a few, somewhere, which do so.

This article needs to be rewritten, taking into consideration the two misconceptions I have set forth here, and any additional comments anyone else wishes to add here. Gene Nygaard 14:12, 17 August 2005 (UTC)

I only claimed that capitalizing the 4.185 kJ calorie as "Calorie" or "Cal" is sometimes used as a notational convention in the U.S. I know that this convention is not followed by the U.S. federal legislator (see 21CFR101.9) or in many/most U.S. textbooks, but I believe it is encountered out there often enough to deserve being mentioned. (It all boils down to the question of whether a Wikipedia article should be descriptive or prescriptive.) Markus Kuhn 16:52, 17 August 2005 (UTC)

"Calorie" for kilogram calories is not peculiar to North America

The use of "calorie" for kilogram calories when discussing food energy is not peculiar to either the United States or to North America. Gene Nygaard 05:55, 4 December 2005 (UTC)

Note that the image on the article page is not a U.S. label, nor a Canadian label. It is a bag of rice from the UK, in Europe. It says

Energy value	1480 kJ
(Calories	350 kcal)

In the U.S., as in the UK, "calories" and "kcal" are the very same thing when it comes to food. (In the U.S., manufacturers also have many of the same difficulties in getting the proper symbols for the untis of measure, though few if any use kJ so we don't see that specific problem.) Gene Nygaard 06:11, 4 December 2005 (UTC)

No, Gene, I'm afraid the misconception is very much yours. On the depicted UK food label, the word "Calories" is just the name of a quantity, not the name of a unit. "Calories" on this label is a technical term for the food energy measured in kilocalories. Note that it appears in the same column as the other quantities. There can be no doubt that this word is not a unit of measurement, since there is a unit of measurement given in the same table row: kcal. You are fighting here for your own personal minority interpretation of the world of calories, without being able to quote any credible references to back up your claims that the kilogram based food calorie is anything other than either a North American unit or a North American short name for kilocalorie. Show me any other authoritative source from outside North America that refers to a kilogram based definition of the calorie before making such radical changes to a perfectly balanced article. I have all the official standards-body literature behind me with the definition of the gram-based calorie. Please provide references rather than personal views! Markus Kuhn 11:16, 4 December 2005 (UTC)

The "quantity" was already named, unlike the typical U.S. label where the word "calorie" is indeed used as s substitute for the name of the quantity.

Can you show me any credible reference using the word "calories" without a prefix and without "kcal" symbol in reference to food. For example, something from anywhere saying that "fat has 9,000 calories per gram"? Gene Nygaard 12:43, 4 December 2005 (UTC)

I found some on the internet; can you find any in print? Wow, Google shows us five of its nine hits for "9,000 calories per gram", and they come from a total of three different sites!

Contrast that to thirty-eight thousand one hundred hits for "9 calories per gram, you can check to see when they quite displaying them if you like. Gene Nygaard 12:48, 4 December 2005 (UTC)

Another source:

AltHealth http://www.althealth.co.uk/services/info/misc/polyols.php

• "Since polyols are only partially absorbed by the body, they have fewer calories than sugar. Polyols range from 0.2 to 3 calories per gram, compared to sugar with 4 calories per gram."

For those who like to claim that the reason for some UK usage is that it comes from the United States, here is information on the owner of the site, a UK national (Wakefield, West Yorkshire, not Wakefield, Massachusetts) who identifies the web designer as his son. Gene Nygaard 13:28, 4 December 2005 (UTC)

More searches

Google	hits
calories
"nine calories per gram"	920
"9 calories per gram" site:.uk	845
"9 cal per gram"	1,380
"9 cals per gram"	14,600
"9 cal/g"	179
"9 cal/gm"	224
"9 cals/g"	107 (showing 40)
"9 calories (38 kJ) per gram"	won't do exact search
"9 calories/gram"	265
"9 cal/gram"	950
kcal
"9 kilocalories per gram	353
"9 kilocalories per gram" site:.uk	4 (showing 3)
"9 kcal/g" site:.uk	74 (showing 46)
"nine kilocalories per gram"	28 (showing 19)
"9 kcal per gram	195
"nine kcal per gram"	25 (showing 5)
"9 kcal/g"	13,200
"9 kcal/gm"	589
"9 kcal/gram"	119

Using http://www.google.co.uk/ also gives 845 hits for "9 calories per gram" site:.uk Gene Nygaard 14:08, 4 December 2005 (UTC)

Peter Roget, Roget's Thesaurus of English Words and Phrases, 1911? or later Project Gutenberg

382. Heat -- ...
  [thermal units] calorie, gram-calorie, small calorie; kilocalorie, kilogram calorie, large calorie; British Thermal Unit, B.T.U.; therm, quad.
Gene Nygaard 15:04, 4 December 2005 (UTC)

Marcus, even a British transplant like you should be more aware of the world around him. I'd like to hear from any native English-speaker from the UK who is willing to stick his or her neck out and claim that it is not common in the UK to use "calories" to mean the large calories when discussing nutrition and diets. Any takers willing to claim that they never or rarely run into this usage? Gene Nygaard 15:30, 4 December 2005 (UTC)

Confusing sentence

I'm not quite sure whether this is accurate:

The energy liberated from the explosion of 1 ton of Trinitrotoluene (TNT) is equal to 1 billion calories (by definition; see the megaton entry).

Firstly, I see from the entry for TNT that it this should be thermochemical calories. Secondly, does that mean that the definition of thermochemical calories is related to the energy released by TNT, or is TNT somehow defined by the energy that is released? If the former, this should be mentioned above where thermochemical calories are first mentioned. If the latter, I fail to understand how this works. I also think we should use a different mass of TNT to avoid the use of billion, which is an ambiguous value (in UK English it traditionally means 10^12, not 10^9 as it is being used here).

I will fix the first and third of these, although feel free to revert me if you disagree. Somebody else really needs to clarify the second.

Derivation

It would be nice if the article said where the word "calorie" comes from. EdDavies 19:30, 9 February 2006 (UTC)

How to measure the calories?

anybody knows?

unsigned comment by 209.30.240.182 (25 March 2006)

Scope

Please keep the calorie article focused on the unit of measurement for energy of that name, with a few notes on its particular use in food-labeling regulations. More detailed discussions of all other issues related to human nutrition, diet, weight control, etc. really belong into articles of their own. In particular, please do not spam the article with countless URLs to the many advertisement-financed web food/exercise-calories tables out there. Markus Kuhn 17:15, 14 June 2006 (UTC)

Web-based calorie sites

Agree with Markus that this category should not be spammed with food calorie table URLs. But to the extent that they are here, marketing claims relating to the numbers of foods should be required to be more detailed and accurate. Most data falls into the following categories:

• Basic foods (usually from the USDA list)
• Restaurant foods
• Packaged foods, from the Nutrition Facts labels
• Composite data, usually computed for recipes

Specifying separate figures for each category makes it easier to evaluate the quality of each web site's data. for TheDailyPlate, in particular, is really suspect and amounts to a marketing claim by the proprietors of the site. It seems to mostly be data of type #4, mostly from RecipeZaar, which is of dubious use to most people. It also tends to be inaccurate, since RecipeZaar automatically computes calorie counts from ingredients using USDA-derived data, and simply omits ingredients that it cannot match. As a minor side feature of a recipe site, the calorie counts have not been given much attention or priority by RecipeZaar.

Perhaps a format like this would be good:

• Mr. Calorie. Claims 45,000 calorie data as follows: USDA basic foods; 5,000 items from 50 chains updated quarterly; 10,000 items from 100 chains screen-scraped from competing web sites and not updated (includes duplicates); 13,000 packaged foods, 2,000 entered by our staff, 11,000 screen-scraped from other web sites; 10,000 recipe calories from RecipeZaar

unsigned comments from 203.216.99.78 (28 June 2006) and 203.216.101.161 (16 July 2006)

so how do they calculate "calories burned" when exercising? Seems like there was some equation linking energy with "work" but I don't recall... Anyone know?

unsigned comments from Acconnel (27 July 2006)

Contradictory first paragraph

I am trying to understand what a calorie is but this contradiction makes definition unclear. Can someone who knows please fix this!? First: A calorie is a unit of measurement for energy. Then: The word "Calorie" is often mis-used to mean "energy" Thanks! user:rusl

There is no contradiction here: "fat" is the name of a unit of measurement (a reference measure), while "energy" is the name of a quantity (something that can be measured). Some people fail to see the conceptual difference between quantities and units and misuse the names of units (such as "calories") to denote quantities. They say "this snack contains a lot of calories" instead of "this snack contains a lot of energy". (The lack of distinction between unit and quantity is particularly pronounced in American English, where a common remedy seems to be to add the suffix "-age" to a unit name to turn it into a quantity, e.g. "amperage" and "footage" for quantities such as current and length.) Markus Kuhn 12:47, 22 March 2007 (UTC)

While the units of measurement are different from quantities, I still believe both of the above mentioned sentences are basically correct. Even if they are not, I don't see how it is a significant enough issue to warrant inclusion in the article, let alone the first paragraph. If anywhere, perhaps it should be in units of measurement. Benna 02:47, 29 March 2007 (UTC)

I struck the last sentence of the first paragraph, as it was beyond confusing. I think it would be a good idea to spread this understanding of units versus what the units measure, and "Calorie" is a good example of that, but not in the introduction to this specific unit. This confusion only seems to happen with the word "high-calorie", not the word "calorie". One would never say something is tall by saying it's "high-feet", so I think this should be part of the "Calorie" page, but definitely not in the intro. 76.167.124.179 21:56, 15 May 2007 (UTC)

Elevation: At what elevation does this definition of a calorie apply? We know that the energy required to heat water is greater at higher elevations, but I don't see/know anything about if there is a standard in this definition. If there is not, it seems like the definition in fact defines very poorly. — Preceding unsigned comment added by TooManyTooMuch (talk • contribs) 21:39, 21 January 2011 (UTC)

The definition specifies that standard atmospheric pressure is to be used; pressure is what typically varies with elevation, leading to the variations you're thinking of. So you can think of the definition as using sea level as elevation; but the elevation isn't really what matters – what matters is the ambient pressure. Eddy. 84.215.6.188 (talk) 12:00, 11 July 2011 (UTC)

Question: Calories Burned? is there an equation somewhere?

so how do they calculate "calories burned" when exercising? Seems like there was some equation linking energy with "work" but I don't recall... Anyone know?

energy = work Markus Kuhn 10:25, 11 April 2007 (UTC)

Thank you Markus ;^>

However, for the sake of the original questioner, who might not be able to fill in the details: consider someone with a body-mass of about 100 kg (220 lb); on Earth's surface, gravity pulls at just short of 10 N/kg, so they weigh nearly 1000 N or one kN (kilo-Newton); suppose such a person climbs stairs to a floor that's a little over 4.2 metres (e.g. 14 ft, so up about two floors in a somewhat compact building) above where they started; they'll have done (multiplying weight by height) about 4.2 kN.m = 4.2 kJ, i.e. 4200 Joules, of work; dividing by approximately 4.2 Joules / calorie this gives about 1000 (short) calories or one long Calorie. So a 100 kg person climbing two floors of a compact building "burns" about one long Calorie; that's about a quarter of the energy content of a gram of sugar, so they'd need to climb about eight que no que no que no. que no que no que no estas menso cacada ai ki esta. @That_Niggah_Legaceyy (x

ilable, you divide the answer by the unit you want it in (4.2ish J for the short calorie, 4200ish J for the long Calorie used in food labelling).

Of course, if you know your body-mass in pounds and the height in feet and want to measure the energy in long Calories, you're going to need a factor of (pound-weight)×foot/Calorie = 9.81 N/kg × kg/2.2 × 0.3048 m / (4200ish J), which is about 0.000324 or 1/3087; so (body-mass in lb)×(height climbed in ft)/3087 = (energy burned in Calories).

More generally, the energy you burn depends on what work you're doing; usually it's not as simple as lifting yourself through a vertical height, but that should serve as a reasonable rough guide with which to model other activities. If you lift weights, multiply the height you lift the weight through by its weight and the number of times you lift it. If you run, a crude model would say your body moves up and down, in each stride, by a moderate fraction of a metre, say 0.4m; multiply that height by your weight as above and the number of strides you ran (which, in turn, you can estimate by the distance you ran divided by the length of your typical running stride; which is likely a metre or two). Other forms of exercise may be harder to estimate – I'm afraid you'll have to do your own home-work on that !

Then you might also want to take into account the efficiency of the human body; when I climb stairs, I get hot as well as gaining altitude, so I'm actually expending more energy than the above takes into account; and when we digest food, we don't get all of the energy content out of it (partly because we expend energy in extracting the energy content from it); but maybe food-packaging calorie-counts take the latter into account (I've no idea). Eddy 84.215.6.188 (talk) 13:11, 11 July 2011 (UTC)

Question: Calories

Why is the fat measured by the weight of animal that consumes, as opposed to the SI unit for water which is volume??

1kg water equals 1 liter water, so it doesn't really matter

In any case, the calorie isn't an SI unit. If you want to comply with SI standards, you have to use the Joule instead, and the only reason most people don't is because consumers have gotten so used to using calories, the same way they're used to pounds and miles.

Actually 1 kg water is just approx. 1 liter. Also it would be nice to have an exact value onhow many Joule a Calorie is.

1. 1. 1. It is difficult to say how many joules a calorie is. A 15° calorie is 4.1858 joules, and the international steam table (IT) calorie (4.1868 joules). There are also other types of calorie. In bomb calorimetry which is used to calculate enthalpies of chemicals (and foods ie. their calorific content, a calorie is defined as the amount of heat liberated on combustion of 1g of pure benzoic acid.)NB- water can also be used in bomb calorimetry of food83.245.22.39 17:02, 3 January 2007 (UTC)AB83.245.22.39 15:10, 3 January 2007 (UTC) ####

The calorie is measured by the mass of the water it heats because water's density depends on its temperature. If you were defining the calorie by the volume of the water, you would have to choose whether to use the starting volume of the water or the end volume (after it's been heated by 1 °C).

You have to do so anyway since specific heat is temperature dependent also. JIMp _talk·cont 20:57, 15 July 2010 (UTC)

If you warm a given mass of water, its mass is still the same at the end (give or take relativistic corrections O(10⁻¹³), which are dwarfed by the O(10⁻⁴) experimental errors in measurements anyway) but its volume shall have changed. So if you measure the energy it takes to warm a body of water from one temperature to another, dividing that energy by the mass of the water doesn't depend on whether you measured the mass before or after warming; whereas dividing the energy by the volume of the water does depend on whether you use the water's volume before warming or after warming, since these two are different. (Of course, you next also divide by the temperature difference, but that's not at issue here.)

The reason why one has to specify the temperature range over which one is defining one's calorie is that the heat capacity of water does in fact vary with temperature; it's a little over 4.2 J/g/K for short temperature intervals about 4C and appreciably less, below 4.19 J/g/K for temperature intervals near 15C. It remains that (at a given pressure, usually atmospheric) the amount of energy needed to warm a body of water from one temperature to another is proportional to its mass and the ratio of energy/mass doesn't depend on whether you measure the mass before or after (as long as no appreciable amount of evaporation is happening). Eddy. 84.215.6.188 (talk) 13:31, 11 July 2011 (UTC)

Kcal

How is it that a kcal is equivalent to 1 cal when it is also listed as 1000 cal.

I think there is a mistake in citing the number of calories in a pound of body fat. It should be 3500 kcal and 3500 calories.

This helped me! It comes from Spanish Wiki...

1 kcal = 1 Cal = 1000 cal = 4,184 kJ = 4.184 J--Arcillaroja (talk) 17:12, 2 November 2008 (UTC)

Grams and kilograms

I've restored the units to the definition of a calorie (little c), because (a) that's what the international definition is, and (b) 1 mL of water is 1 g only at specific temperatures (technically only one temperature value). -- MarcoTolo 20:47, 5 March 2007 (UTC)

Mature article

I believe this article has reached a high level of maturity and there is little further to improve. The vast majority of edits that we see make it worse and seem to be done by people who do not even bother to read the full article, the references or the talks page. In fact, I now find it regularly necessary to undo about month worth of edits just to keep it in good shape. I think it would be a good idea to give the article some more protected status at this point. Markus Kuhn 10:32, 11 April 2007 (UTC)

Calories and weight gain

The introductory paragraph of this article contained a comment to the effect that a given number of calories could be expected to produce a certain weight gain in the average person. Given that this makes no reference to exercise, or to the food type whereby that energy is consumed (fat is more likely to be stored and result in weight gain than is carbohydrate, in moderate quantities), and given that the comment was dramatically out of keeping with the subject matter of the rest of the paragraph (discussed energy, units, the use as a measure of food energy, and then suddenly a comment on weight gain), I decided that the comment was both spurious and stylistically incongruous, and deleted it. I really don't think it belongs there. cmsg —The preceding unsigned comment was added by 86.31.109.93 (talk) 01:22, 23 April 2007 (UTC).

I also agree with the statement that there's no cause to highlight in the first paragraph the distinction between a quantity, and a unit thereof.

Counter Opinion Regarding Calories and Weight Gain

BUT isn't there recent research calling into question this traditional conclusion that fat is more likely to be stored than carbs? Isn't there research calling into question the correctness of traditional calorie counts of food, because the original research methodology for measuring these calories is not equivalent to the biological processes within the human body? Shouldn't there be reference to these controversies in the article?

Meh. Probably makes more sense to have a generic mention, in the opening, of the fact that nutritionists make a big deal of energy content, expressed in long Calories, and link to some general discussion of nutrition. Put the controversy there, where it belongs, rather than on a page that defines the archaic unit (which contains enough complications as it is, what with the glorious absurdity of "calorie" also serving as a synonym for kilo-calorie, compounded by the diverse choice of temperature ranges over which to measure the heat capacity). Eddy. 84.215.6.188 (talk) 13:39, 11 July 2011 (UTC)

I agree. There's a note at the top directing readers to the article Food energy which is the appropriate place to talk about ... food energy. This article is about the unit ... or units. JIMp _talk·cont 14:51, 11 July 2011 (UTC)

Terminology

1 cal_INT = 4.1868 J (1 J = 0.23885 calIT) 1 cal_th = 4.184 J (1 J = 0.23901 calth) 1 cal₁₅ = 4.18580 J (1 J = 0.23890 cal15)

Can someone explain what the subscripts mean?

Without actually knowing the answer, I'd be willing to guess that INT is an INTernational calorie, th is a thermochemical calorie, and 15 is a 15°C calorie. These are described in this section. --86.148.122.55 19:45, 13 August 2007 (UTC).

Calories and weight loss

1 pound is equivalent to approximately .45 kgs, so the weekly kcal deficit or surplus to lose/gain one kg should be less than that required to lose one pound.

According to the paged sourced, http://www.nlm.nih.gov/medlineplus/ency/article/001940.htm , the weekly deficit/surplus required to lose/gain one kg/week is around 1600 kcal. (0.45359237 x 3500 kcal). That translates to a reduction of 500 kcal/day to lose one pound a week, and approximately 230 kcal/day to lose one kg.

A reduction in calorie intake by 7800 kcal/week, a reduction of more than 1000 kcal/day, is potentially dangerous. Maybe it should also be specified that the numbers stated are per week and not day, since they could get mixed up. —Preceding unsigned comment added by 213.113.219.51 (talk) 21:37, 6 December 2007 (UTC)

Are these all kcal or cal? —Preceding unsigned comment added by 122.167.218.224 (talk) 12:00, 6 January 2008 (UTC)

Counter comment on discussion above I think this comment is total hooey. If you reduce your calorie intake by 500 calories below a maintenance level, you turn off your metabolism, which makes weight loss more difficult. Moreover calories, i.e. the amount of heat produced when foods are tested in oxidation reactions in a laboratory, have little or nothing to do with how food is metabolized in the body.

What kind of Calories are on nutrition labels?

According to this article there are many kinds. But, which ones are used to measure food energy(at least for U.S. food companies). 207.177.111.36 (talk) 15:01, 7 December 2007 (UTC)

Go back in the article's history about a year, and you'll find it all explained in great detail. This article has recently been edited to death and needs resetting to an older state. Markus Kuhn (talk) 10:44, 6 March 2008 (UTC)

Numbers need citation

I looked all over the internets and couldn't find clear sources for kcal/grams of fat, protein or carbohydrates. Some books that I've read say that carbohydrates are actually 3.75kcal/g. Needs clarification and citation. Thanks--70.74.82.114 (talk) 22:58, 5 January 2008 (UTC)

Check out food energy for the information you are looking for. Markus Kuhn (talk) 17:52, 30 March 2008 (UTC)

Confusion between kilocalorie and Calorie

Most people coming to this article will be looking for the definition of Calorie (that's large Calorie, the one used to measure food energy content), which is a kilocalorie. This article does not make the distinction very clear. That's because it's a mish-mash of rubbish written by obsessive nerds with no mind for the target audience of, or proper scope for an encyclopaedic article. Ah well, I suppose that this is Wikipedia.

Wikipedia (n): A mish-mash of rubbish written by obsessive nerds with no mind for the target audience of, or proper scope for an encyclopaedic article. —Preceding unsigned comment added by 121.45.143.14 (talk) 11:31, 16 March 2008 (UTC)

The confusion is in the real world; not in Wikipedia. It is easily avoided—just stick to joules. Gene Nygaard (talk) 03:25, 31 March 2008 (UTC)

Hear! Hear! Jɪmp 03:28, 31 March 2008 (UTC)

Wait a minute; let me rephrase that.

There is no real confusion, either in the real world or on Wikipedia, for a couple of reasons:

• There are only 27 or 28 surviving dinosaurs anywhere in the whole world who ever still use calories to measure anything in sciences such as chemistry and physics. Nobody uses them any more, the rare confusion might come in something more than 60 years old. The only calories in use today are the ones in the medical sciences and everyday use, the food calories. The small calorie is essentially dead.
• Nobody ever uses prefixes with the large calorie. So if you see "kilocalories" you know that this is somebody who wants to appease the old users of the small calories, not realizing that such users don't exist any more.

So if in the context of modern usage, you hear somebody say "calories" (or even if you have really good ears and hear them say "Calories"), or if you hear them say "kilocalories", they are all the same thing. Doesn't matter in the least which term you use. There is no real confusion, just an imaginary one by people oblivious to the world around them. Gene Nygaard (talk) 03:41, 31 March 2008 (UTC)

They use the term kilocalorie in Japan. Jɪmp 03:50, 31 March 2008 (UTC)

Food marketing industry of course tries to establish the "large calorie" as a valid or even just practical or necessary unit. So there is plenty of motivation and money behind creating a completely un necessary unit that does not make any sense except to confuse consumers. If the large calorie symbol "Cal" becomes "established" we may soon see e.g. travel agencies inform you about e.g. the distance from the hotel to the beach in large meters "M". So be prepared to walk 10km (10 000m) instead of the 10m you may have been hoping for. I may also prefer to refer my body weight or the one of my child in "large gramms". I can see weight conscious people claim to weigh 100G rather than 100kg who could hear the difference. Apart from the fact that it is completely unnecessary it only works in writing - it can only be seen as a joke or bold marketing stunt by a greedy industry that tries to sell us high energy food.

So in case a peanut butter producer adds the funny unit again into this article I post my modification here so that people can re-correct it if they like... let's hope that we consumers win this battle and not the PR departments of high energy yummy foods :) - alternatively we could - just for fun - start introduce "large" meters or grams on the other unit definition pages - this would be fun or at least a great joke and some industries will love it!

So here is my suggested and saved version for those interested in providing serious information:

One calorie (symbol: cal) is the amount of heat (energy) needed to increase the temperature of one gram of water by 1 °C. 1 cal is about 4184 J. "J" is the symbol for the official unit for energy, the "Joule". 1 kcal = 1000cal hence 1kcal is 4184 kJ. "k" is the official pre fix for units meaning "kilo" or a 1000 units of something e.g. 1kg = 1000g.

[Note, in recent decades the unit "calorie" has been "modified" (presumably for marketing purposes in the food industry) to conceal high energy content in food and confuse customers - especially in developed countries with high numbers of overweight people.]

Sometimes, on food labels, you may find "calorie" spelled with a large "C" e.g. "Calorie" or "Cal" to hide the fact that it contains actually 1000 calories - not just "one" calorie. The "inventors" of this unit gave it the name "large calorie" sometimes also referred to as "kilogram calorie". As this "unit" only works in writing - and is completely unnecessary - it makes no sense to use it other than confuse consumers.

The "calorie" - as opposed to the official energy unit "Joule" - is commonly used to express food energy, e.g. when discussing dieting or nutrition plans or simply reading the energy content on food labels. This is probably because 2500 kcal is smaller than 10000 kJ, the recommended energy intake for an adult person per day. —Preceding unsigned comment added by 220.245.124.221 (talk) 17:58, 23 October 2008 (UTC)

Heat

Revision as of 21:51, 27 February 2008 by User:Unfree was anything but "Minor rewording". Amongst other things,

A calorie is a unit of measurement for energy.

was changed to

The calorie is a unit heat, a form of energy.

This is a major change. The unit now only applies to energy in the form of heat. Has the unit been dropped from nutritional labels recently? Food energy is certainly not a form of heat. I'll be reverting this substantial change. Jɪmp 07:36, 30 March 2008 (UTC)

ISO 31-4 (Annex B, informative, referenced) describes the calorie as a unit for the quantity "heat" or "quantity of heat". Recall that food energy was historically defined by using a bomb calorimeter that measured the amount of heat given off when you burn the food in a high-pressure oxygen atmosphere. The definition of the calorie is certainly a measurement of heat. All these suggest that describing the calorie as a unit of heat is perfectly correct. I'm therefore reverting your reversion. Markus Kuhn (talk) 10:18, 30 March 2008 (UTC)

Here's a web reference about the SI systems and calories under "Other unacceptable units": http://physics.nist.gov/Pubs/SP811/sec05.html#5.1.4 that could be useful in a few places relating to the SI. Calories in food are potential or eventual calories - we "burn" calories in our muscles etc... Ephdot (talk) 11:55, 30 March 2008 (UTC)

It might have been measured by means of conversion into heat but food energy is a form of chemical energy not heat. We may colloquially use the word burn but muscles are not heat engines, they produce heat but as a by-produce, they don't convert that heat to work. If ISO 31-4 describes the calorie as a unit of heat, they ignor common practice ... or common practice ignors ISO 31-4. Jɪmp 00:49, 31 March 2008 (UTC)

The calorie has a lot of historic baggage, so this article will have to address that. As I understand it, the difference between a unit of heat and a unit of (mechanical) energy/work had mainly to do with managing measurement uncertainties. Historically, the thermal capacity of water was not known (or defined?) precisely enough to agree on a high-accuracy conversion factor between heat and mechanical forms of energy or work. Therefore, independent units were defined for both originally. In laboratory practice, the energy released in exothermic reactions (e.g., food energy) has been quantified in the form of heat, therefore historically using the unit of heat rather than the unit of mechanical work was the obvious choice. Chemists could calibrate their equipment and compare measurements without having to worry about what all this meant in terms of force·length. I'm not sure whether we would do a proper service to Wikipedia readers if we restricted our horizon to interpreting the current edition of the online version of the SI Brochure in a strictly dogmatic manner (the truth as laid down in the holy scripture by the last CGPM proceedings editor), and neglect any of the historic reasoning and motivation behind the unit, something Gene Nygaard seems to prefer. The calorie remains a unit of heat, and the fact that we have now agreed exact conventional conversion factors to the SI unit of energy doesn't change that historic truth. Markus Kuhn (talk) 21:57, 15 June 2008 (UTC)

Both current use and historical use should be thoroughly covered. The current version of the article doesn't do this. The first sentence, "The calorie is a pre-SI unit of energy, in particular heat.", in especially does not do justice to the facts. It's a unit of energy, in particular food energy, historically defined in terms of heat. JIMp _talk·cont 01:26, 16 June 2008 (UTC)

Weird notions about usage

Some people (most recently User:Markus Kuhn, but others in the past as well, such as 121.45.143.14 above) seem to have some weird notions, such as:

• Americans normally capitalize the initial "C" in food calories, or
  • more generally, that all people do.
• That people in the UK and some other places don't use the word "calories" for large calories, but instead use small calories and attach the prefix "kilo-" at the scale used in nutrition measurements.

That is a crock of nonsense.

• For the first point, take a look at Image:Nutritionfacts.png.
• For the second point, consider these Google results:

Google	hits
calories site:uk	320,000
kilocalories site:uk	2,390

How many of those 320,000 do you suppose refer to food calories? Gene Nygaard (talk) 04:02, 31 March 2008 (UTC)

Here's an interesting tidbit, even if it probably doesn't fall into he category of a reliable source:

Yahoo!Xtra Answers http://nz.answers.yahoo.com/question/index?qid=20080308001534AAw38Ok

Resolved Question

How many calories is 331 kcal?

* 3 weeks ago

Best Answer - Chosen by Voters

331 calories.

Kcal is the scientific term, calorie is the common term

* 3 weeks ago

Looks like it might have been the only answer, but I might word it a little differently while basically seconding it; the distinction between symbols and words is also a factor, just as in the case where many people continue to use microns, despite the CGPM having told us not to do so 40 years ago, but almost nobody uses the symbol µ for them any more—even the dinosaurs who hag onto the outlawed word now usually use the proper symbol µm with that word, rather than its former symbol. In other words, there can exist changes in usage of either the spelled out words or of the symbols, somewhat independent of each other. Gene Nygaard (talk) 13:34, 31 March 2008 (UTC)

Common usage is indeed a relevant part of the story. All the same, I just went and looked at a bag of sugar in my kitchen cupboard and it (in Swedish) lists the energy content per 100g as 400 kcal and as 1700 kJ. So perhaps the anglophone world does conflate the Calorie with the kcal, but don't assume the same is true for the rest of the world ! I will hazard a guess that the EU has issued a directive on food labelling that requires the use of kcal and forbids the use of Calorie; with the result that, in England, one must read "kcal" as "Calorie" (and naturally no-one can hear your capitalisation) to have your hearers understand you.

I think the most appropriate way for an encyclopædia article to deal with this is to state that the name is used for two units; to list the two units – with their "full" names, short calorie and long calorie, so that later text can refer back to them unambiguously – giving the definition of each; then to briefly explain the history and where it has left us – the short calorie was a scientific unit of measurement, now deprecated by SI; the long calorie entered the vernacular as a short-hand used in the context of nutritional energy and has survived; it is sometimes called Calorie, capitalised, in an attempt to limit confusion; and that, in practice, any use of "calorie" without a kilo-prefix means the long calorie while any use with the prefix means the short calorie, with the mildly perverse effect that dropping the kilo-prefix doesn't actually change how anyone is going to interpret it. Eddy 84.215.6.188 (talk) 14:25, 11 July 2011 (UTC)

Also, in defence of the "long" calorie, it does actually make more sense to use the kg as unit of mass, since that's the unit that's used in building up the Joule as kg.(m/s)²; an "energy per unit mass" is a squared velocity so its natural unit is the square of your system's unit of velocity. Not that this is of any but historical interest; the unit is archaic. Eddy 84.215.6.188 (talk) 15:26, 11 July 2011 (UTC)

"in particular, heat"

The change to that wording is a slight improvement, Markus Kuhn. But still slightly off. In comparison, note that Resolution 3 of the 9th CGPM (1948) says "The unit of quantity of heat is the joule."

Yet, I doubt seriously that you would claim that this limits the joule to only measure that kind of energy and not any other kind of energy and not the quantity called work (physics). So why are you being so foolish with respect to the calorie? Gene Nygaard (talk) 13:17, 31 March 2008 (UTC)

"... in particular, food energy ..." if anything (and, no, I don't buy the you-burn-the-food-to-measure-the-energy argument). Maybe historically a measure of heat but not today. JIMp _talk·cont 11:33, 27 January 2009 (UTC)

I don't think it's really faithful to describe it as a unit of heat; it's really a unit of chemical energy, measured by exploiting the early-established equivalence of chemical and thermal energy (later recognised as equivalent to mechanical work). So it's expressed in terms of the extent to which water is heated by a chemical reaction, i.e. by a measure of heat, but it always was primarily a way to thereby measure the amounts of chemical energy.

How about:

The calorie is a unit of energy now primarily used for the chemical energy content of food. It was previously used for chemical energy generally, as determined by the extent to which the energy liberated by a reaction would heat a body of water; however, in scientific use, the Joule is now favoured.

Then deal with its brief history, the dichotomy between short and long forms, etc. Eddy 84.215.6.188 (talk) 14:25, 11 July 2011 (UTC)