[Ben Bleiman]

Ben Bleiman asked the Naked Scientists:
   
Hello Naked Scientists,

I have heard from several people that if I am trying to cool off on a hot day that room temperature water will do a better job than ice water.  How can this be?  The only way I can think of would be when you drink the ice water your metabolism has to speed up to bring that water up to body temperature.  While the ice water would be removing more heat from your body you would feel hotter in the long run.  Is this true?

What do you think?

[DrN]

I know they drink a lot of tea in hot countries, rather than cold drinks, so there must be something in it. The metabolism reason does ring a bell, I'm sure someone explained it to me like that before.

I also think I heard someone say that if you drink a very cold drink, it causes the blood to be diverted inwards to the centre of your body to deal with it, whereas if you drink a hot drink, blood is diverted to the skin, where it is more effective at cooling you down.

[Yomi]

Thats false i would suggest my reason later !!!! Hang on o.k

[Madidus_Scientia]

So what if it diverts blood inwards to deal with it, after its 'dealt' with it that blood will be cooler, so your overall body temp should be too

[dentstudent]

Quite. If you drink ice-cold water, the core temperature of your body decreases drawing blood away from external sources, therefore reducing your heat-loss. If you drink hot drinks, the core temperature increases, blood goes to the skin and external surfaces and therefore increases heat-loss, which will cool you down.

[Don_1]

Cold drinks may have a temporary 'feel-good' effect, but a hot drink, such as tea, will cause an increase in sweating, thus helping to cool the body over a longer period.

[sunflower]

I think I've heard that hot water will freeze quicker than cold water in icy weather conditions. I don't know how that can be either!

[Chemistry4me]

There was this thread about it as well as this one.

[Fortran]

You are all assuming that the regulatory temperature function somehow overcompensates, it does not. If you want to keep cool, drink cool.  Think about it, suffering from Hypothermia, do you give them Iced water or a nice hot cuppa joe? 

Drink hot tea on a hot day you will sweat more than than if you drink cold, but your body will attempt to regulate whichever way you push it. I also understand that drinking Ice water after hot heavy exercise can cause vomiting, thus warmer fluids are used.