I have a question about how a calorie works. I believe the definition of a calorie is the amount of energy required to raise the temperature of 1 gram of water 1 degree celius. Now I'm not all that keen on transferring things from metric, but looking online, it appears there are approx 450 grams in 16oz of water.

Now if I drink just one glass of "ice cold" water, I don't know how much it has to increase the water to get it to body temperature, but it is quite a bit. Multiply that temperature change by 450 grams per galss, that's a ton of calories, or so it seems. How does this not factor into the amount of calories we use per day, and how are we not in a huge deficit every day because of it?

I also apologize if this has been discussed before, but searching for terms like "calorie" and "water" brings up tons of hits as you can imagine.

Keep in mind that a calorie is active energy expenditure. Your body can also passively warm the water just by "running it through your pipes." In other words, the water is also heated just by coming in contact with your body, as well as actively warming it in your digestive tract, which does take energy.

Interesting question. And to make matters more complicated, remember that the body is usually trying to cool itself down by means of evaporation of sweat...

Interesting question. And to make matters more complicated, remember that the body is usually trying to cool itself down by means of evaporation of sweat...

True, but the majority of the calories your body spends every day is to heat itself. Looks like it's kind of a double-edged sword! :)

Your body can also passively warm the water just by "running it through your pipes." In other words, the water is also heated just by coming in contact with your body, as well as actively warming it in your digestive tract, which does take energy.

Yeah, but .... when the water is heated due to contact with the (warmer) body, the body will be cooled very slightly. So the question then is: does the body do some extra work in order to restore the original temperature?

Yeah, but .... when the water is heated due to contact with the (warmer) body, the body will be cooled very slightly. So the question then is: does the body do some extra work in order to restore the original temperature?

Evaporation only occurs on the outside of the body. So, if you pour a glass of water on your arm, then the body is cooled. But this cooling is passive. If your body is cooled too much, then yes, it will spend energy to heat itself more. However, water inside the body doesn't cool the body all that much. Your body is spending energy to heat itself continuously anyway, so the addition of cold water won't really have much of an impact anyway. The water eventually gets heated, but some of this is passive and some is active. Not much extra energy is spent to heat the water because your body is already spending energy as it is to heat itself.

Interesting :)

Maybe that's why drinking COLD water is a part of a weight loss diet :p

Unfortunately a "calorie" is the amount of energy requird to heat one gram of water by 1 degree Celsius.

HOWEVER, the "Calories" you eat in food are actually Kilo-calories so you have to heat one THOUSAND grams of water 1 degree Celsius to burn a Calorie (or Kcal, or Kilo-calorie or whatever you prefer)

In reality, the amount of extra Kcals you burn from heating up water is very minimal, unfortunately.

1000 grams of water (1 kilo gram of water) is about 35 ounces of water. So, THEORETICALLY if you drink 35 ounces of water that is 35 degrees below body temperature, you could burn 35 Calories. Unfortunately, your basal metabolic processes that keep you warm "anyway" will heat a lot of this water, so less then 35 actual Calories would be burned.

-Allen

Although a bit offtopic from the discussions, I read the following post made by rtestes and I found it very informative. Since the discussion turned to ice water, I thought some people would like to check it out.

http://forums.johnstonefitness.com/showthread.php?t=17385

I don't know how to setup the link to direct to his post specifically, but his is the last in the thread.

Wow, restes does go into detail about water and fatloss.


Read it here. (http://forums.johnstonefitness.com/showpost.php?p=167393&postcount=5)

That's a link to the actual post for the lazy ones ;)

Ah... thanks for the bit about a calorie being 1000x, hadn't heard that before, though I do remember people saying kcal around here and never understood 100% what they meant.

Also interesting article posted by restes.....

HOWEVER, the "Calories" you eat in food are actually Kilo-calories so you have to heat one THOUSAND grams of water 1 degree Celsius to burn a Calorie (or Kcal, or Kilo-calorie or whatever you prefer)
-Allen

This is something in the back of my head that I knew, but I totally forgot about it. Shame on me, and thank you for reminding my forgetful head! :tu:

My OPINION is below:

I think its more of a constant. Science defines it in that particular way, i.e. 1 calorie can raise the temp of 1 gram water by 1 celsius. If this statement is met, then BY DEFINITION, its a calorie.

I dont think drinking water would have an effect on calorie use (not as much as your saying anyway!), i think its just some sort of a comparison.

put it this way, if you for instance ate a 4000 calorie diet for bulking and drank lots of water (eg 2000 grams), would you burn your calories by just sitting down ? lets say you drank 2000 grams of water at once, would your body go into heat overdrive ? im not so sure, but thats what i think.

so would we burn loads of calories by just drinking loads of grams of water ?

However, water inside the body doesn't cool the body all that much.

To whatever extent the water gains thermal energy, the body will lose the same amount of thermal energy. If 1 calorie of energy is transferred to the water, 1 calorie is transferred from the body.

I don't understand the distinction between "active" and "passive" heating.

so would we burn loads of calories by just drinking loads of grams of water ?

Not loads. You would burn slightly more calories by drinking a lot of cold water.

I think you're taking the definition of a calorie too literally.

Basically a calorie is a unit of measure. Think like voltage, watts, grams, metres. Using one calorie in your body does not mean you have within your body raised the temperature of one gram of water by one degree C. It means that the equivelant energy that is needed to raise one gram of water by one degree C has been used by your body for various functions. Stuff like digestion and muscle movement. You can use the calorie on machinery if you like. It's just a quantity of energy, the prefered measure for nutrition and measuring the human body's energy use.

Yes the water will probably have its temperature altered by homeostatic mechanisms, but it's not as simple as you are assuming.

The active vs. passive heating of the water refers to whether your body begins to burn more calories to warm itself back up. In passive heating, the waste heat generate through chemical reactions will warm the water instead of escaping your body (through sweat, radiation, etc.). In active heating your body will intentionally burn more calories to warm itself (think shivering). To what extent these processes are used for a glass of ice water, I have no idea.