Talk:Calorie

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[edit] 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: "calorie" 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)

[edit] 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)

[edit] 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

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?

[edit] 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)

[edit] Question: Calories

Why is the calorie measured by the weight of water it heats, 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. 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).

[edit] 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.

[edit] 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)

[edit] 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)

[edit] 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.


[edit] 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?

[edit] Terminology

1 calINT = 4.1868 J (1 J = 0.23885 calIT) 1 calth = 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).

[edit] Need More Background on The ThermoChemical Calorie.~

The International Table Calorie is now defined as 4.1868 Joules in accordance with the determination of the fifth International Conference on Properties of Steam (London, July 1956). This detaches the calorie from the properties of water and yet retains a value very close to the properties of water.

The ThermoChemical calorie is defined exactly in terms of Joules as well but uses 4.184 Joules. Who gave this definition and what was the reason? What does "ThermoChemical" imply?

[edit] 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.

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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.

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)

[edit] "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)