For every two liters of ice water you drink, you burn 73.9 calories. Here's the math:

specific heat of water x mass of water x temperature change of water = energy

Water has a specific heat of 4.18 Joules/gram*degree celsius, 2 liters of water has a mass of 2000 grams, and if you drink ice water (0 deg celsius) and warm it up to body temp (37 deg celsius) then you will use 309320 Joules

(If you drink room temp water then the temperature change would be only 20 degrees celsius, and the calories burned would be 39.9 calories)

1 Joule is equal to .2388 kilocalories (food calories)

Chapter 6, Thermochemistry, Zumdahl Chemistry (the textbook I use in class)

So drink ice water.

Sorry, couldn't resist - it's summer and I'm suffering a chemistry withdrawl!

Joan