calorie vs. a food calorie

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calorie vs. a food calorie

Postby schmidty5 on March 13th, 2010, 3:16 pm 

In chemistry we talk a lot about the calorie of energy (the energy it takes for 1 gram of water to increase by 1 degree Celsius). Is this different from the calories that we intake in food, if so how?
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Re: calorie vs. a food calorie

Postby Lincoln on March 13th, 2010, 5:11 pm 

A food calorie is 1,000 "chemistry" calories.

That did sound a little like a homework question.
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Re: calorie vs. a food calorie

Postby DrCloud on March 13th, 2010, 5:40 pm 

I've actually heard "kilocalorie" used in connection with food on occasion. Unfortunately, it's not in wide use (yet?). HPH
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Re: calorie vs. a food calorie

Postby Lincoln on March 13th, 2010, 5:41 pm 

If you buy food in Europe, the caloric content is listed in units of kcal.
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Re: calorie vs. a food calorie

Postby schmidty5 on March 14th, 2010, 1:08 am 

no this wasn't a hw question, i just have heard of both of them a lot and i've been wondering for a while why there called different things. Thanks
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Re: calorie vs. a food calorie

Postby Lincoln on March 14th, 2010, 7:11 am 

I just got off a plane in Switzerland, having been given a 150 dL can of orange juice. On it, it gave the energy content of 100 dL of OJ first in kJ, then in parenthetical (kcal).

This was a can from a Belgian source. I cannot confirm that this a European-wide phenomena, but western Europe being what it is, it's probably how it's done across the western part of the continent.
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Re: calorie vs. a food calorie

Postby Nick on March 14th, 2010, 11:27 am 

We use both kJ and kcal in the UK. I would be surprised if the rest of (western) Europe didn't too as we are usually the ones to use different units.
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Re: calorie vs. a food calorie

Postby DrCloud on March 14th, 2010, 11:41 am 

So, back to the OP:

Suppose you're going with the (so-called) recommendation of a 2000 (k)calorie per day diet, and you weigh 75 kg. How many degrees C would your body heat up (assuming a 1000% efficient metabolism)? And, more importantly, why doesn't it? HPH
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Re: calorie vs. a food calorie

Postby schmidty5 on March 14th, 2010, 1:55 pm 

DrCloud wrote: Suppose you're going with the (so-called) recommendation of a 2000 (k)calorie per day diet, and you weigh 75 kg. How many degrees C would your body heat up (assuming a 1000% efficient metabolism)? And, more importantly, why doesn't it? HPH


Ya i was thinking this too. When you eat like a huge steak, why does ur body temp not change all that much?
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Re: calorie vs. a food calorie

Postby MrMistery on March 14th, 2010, 6:33 pm 

actually your body temperature does increase, in the sense that it is kept at an artificially high temperature. Think of a fire: unless you keep throwing wood in it, it will burn out by itself. We keep our temperature constant, and we need food to do that. Of course this is a simplistic way of looking at it, and you do have to think a little bit about biology to work out the difference between a test tube and a human.

@OP
you may also notice that a food calorie is abbreviated a Cal, while a "chemistry calorie" is abbreviated cal. Basically, 1 Cal=1 kcal = 1000 cal

@everyone
the kJ/kcal thing is a regulation of the European Union. You will definitely find it in all the EU countries, but you may not find the same rule in European countries like Belarus or Ukraine.
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Re: calorie vs. a food calorie

Postby Natural ChemE on March 15th, 2010, 1:01 am 

DrCloud wrote:Suppose you're going with the (so-called) recommendation of a 2000 (k)calorie per day diet, and you weigh 75 kg. How many degrees C would your body heat up (assuming a 1000% efficient metabolism)? And, more importantly, why doesn't it?


Conservation of energy. The energy is converted into many forms that aren't thermal, so the theoretical thermal yield isn't approached.

schmidty5 wrote:When you eat like a huge steak, why does ur body temp not change all that much?


Biochemical activities such as building your cells, moving your muscles, etc. all require energy. So your body doesn't turn all of the energy found in food into heat. Instead, your body uses a great deal of that energy to make more cells, move your muscles, etc.

Also, you don't break down that steak all at once. Your body is constantly bleeding heat to the environment, and it's breaking down that steak over a long period of time.
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Re: calorie vs. a food calorie

Postby BioWizard on March 15th, 2010, 1:10 am 

As far as I've used it, Cal=1kcal = 1000 cals. cal is an amount of energy, and should mean the same thing everywhere.

P.S: Requesting help with approaching homework questions is considered OK for this particular subforum, as long as we're not handing someone the final answer to their homework. The OP seemed fine to me.
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Re: calorie vs. a food calorie

Postby Lincoln on March 15th, 2010, 7:18 am 

You mean eating a pint of Haagen Daz ice cream doesn't send your core body temperature up 25 oF?
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Re: calorie vs. a food calorie

Postby BioWizard on March 15th, 2010, 10:11 am 

Regarding DrCloud's question, NCE answered it partially. Not all the energy is converted to thermal (you're an organism, not a bomb calorimeter). In fact, a lot of it isn't. Also, the temperature of your body is tightly regulated (biochemically and mechanically). If you're body temperature is going over the tight physiological limit, your body will respond in ways to help bring it back down (sweat, faster breathing, etc). Alternatively, if it goes below the limit, you start shivering, which also ramps up catabolic processes. It can be regulated by other things, like cytokines (a specific class of molecules) released by t cells (a subset of cells involved in immune function). That's why your temp goes up when you're sick. It helps your body fight back the microbes.
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Re: calorie vs. a food calorie

Postby schmidty5 on March 15th, 2010, 3:11 pm 

BioWizard wrote:P.S: Requesting help with approaching homework questions is considered OK for this particular subforum, as long as we're not handing someone the final answer to their homework. The OP seemed fine to me.


this is seriously not a hw question, i was just curious.
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Re: calorie vs. a food calorie

Postby BioWizard on March 15th, 2010, 3:29 pm 

schmidty5 wrote:
BioWizard wrote:P.S: Requesting help with approaching homework questions is considered OK for this particular subforum, as long as we're not handing someone the final answer to their homework. The OP seemed fine to me.


this is seriously not a hw question, i was just curious.


And that's why I said it's perfectly ok. Had you posted a homework question and simply asked for a final answer, I would've told you to go do your homework by yourself. However, asking questions related to your homework and engaging the others about their answers is perfectly fine for this subsection.

If anyone has any further questions on the matter, please refer to the Beginner Forum's guidelines here and/or post them on the feedback section. This forum has three moderators and they can decide what's OK, what's walking the line, and what's tripping on it. So let's just focus on showing off our elementary knowledge (which I sometimes find to be at least equally fun as advanced knowledge) and not worry too much about the moderation of this forum. That's what the mods are for.

schmidty, were your questions sufficiently answered? Please don't hesitate to ask for further elaboration or post new ones if you have any. That's what this forum is for.
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Re: calorie vs. a food calorie

Postby schmidty5 on March 15th, 2010, 3:36 pm 

ya im satisfied, thank you everyone
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Re: calorie vs. a food calorie

Postby BioWizard on March 15th, 2010, 3:42 pm 

Good. Looking forward to more questions :)
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