Energy Taken For the Body To Heat Water.....

[CoachRoberts99]

Hi Everyone,

 

Ok, was talking to a friend of mine the other day, who said his doctor told him to lose weight, drink a pint of ice cold water.... His logic is it takes 1 calorie to heat 1 gram of water by 1 degree (which is correct) therefore, if you drink ice cold water, the body has to spend calories heating the water to body temperature, and he said that 1 pint would mean your body using an extra thousand calories in heating it up (madness)!!!

 

Now clearly this is the largest amount of b0llocks I've ever heard from a man of science, and as I said to my friend, by that logic when I have a nice ice cold lager, even tho it has 300 calories in it, I would still be losing calories and if I drank 5 pints a day the weight would fall off me, however as my girlfriend and belts would testify this doesn't seem to be the case !

 

The only problem is I can't quite figure out why this isn't the case, as the science of calories is totally correct, so the logic isn't totally mad, and a lot of ways I've thought about it I can't escape the fact that the water is heated, and that DOES take energy to do, and largely that energy has to come from somewhere.... my thoughts are however@

 

1) Something about the bodys natural balance of systems means that actually it doesn't take extre energy to stay at 34 degrees, naturally with muscles, digestive system, cardiovascular the "accidental" heat created is secondary, so if it wasn't used to heat water it would just be lost through the skin, so doesn't add extra workload to the body.

2) Ambient temperature plays a role, that actually your body takes heat from the surroundings, so on a hot day, your body is working less as the surroundings is closer to 34oC.

 

 

What do you guys think?

 

 

Thanks,

 

Matt

 

 

 

 

[insane_alien]

the important fact to note here is the difference between a calorie and a Calorie.

 

you might notice that foods and drinks the energy content is given in Calories while that definition is for a calorie.

 

it helps to look at the short hand, a calorie is 'cal' and a Calorie is 'kcal'

 

the value on the food is 1000*bigger than the thermochemical calorie.

 

so that pint of water with 1000 thermochemical calories only corresponds to 1 food Calorie.

 

so he'd need to drink 1000 pints of water to get the effect he is looking for.

[John Cuthber]

The problem is the confusion between Calories and calories (one has a capital c).

The calories that are the heat needed to warm a gram of water by 1 degree are the small sort. The Calorie (also known as the great calorie or kilocalorie) as used in calculating the energy in food are 1000 times bigger.

It is a damnably stupid set of units.

So, if I drink half a litre of ice water and, in due course, pee it out at 37C I have spent 37 *500 i.e 18500 calories heating it up.

However if I drink a half litre of soft drink I consume (hastily checks label on tin in bin) 205000 calories.

 

 

In fact it's a bit more complicated than that but drinking lots of cold water has a slight effect on body weight, but mainly because, if you are full of water, you are

not hungry.

The direct effect works out at about 2 litres of ice water to use up the calories in just one biscuit. The overall effect is a bit less because the body has systems in place that regulate temperature bt doing things like closing down blood vessels near the skin.

 

Also drinking lots of water isn't good for you anyway.

[CoachRoberts99]

Ahhhhh, I'm such an idiot!

 

Thanks for the prompt replies guys, have to say I'm pretty embarrassed at missing that, got so caught up in rage at such a stupid idea I never stopped to think; but now vague recolections from A-Level physics and sports science have come flooding back!

 

Thanks again,

 

Matt