others have discussed
this idea(see: water has negative calories
), but perhaps I've thought of something new
see, the stated problem with drinking really cold water as a way to lose weight is that you don't lose very much. the actual math works out to you losing about 1 calorie per ounce of ice water you drink. (every time I talk about calories here, I am really talking about kilo-calories)
So this doesn't work all that well. But then I thought: what if, instead of drinking water, you ate ice? It takes one calorie to raise the temperature of one kilogram of water one degree Celsius. However, it takes 80 calories to change one kilogram of ice to water. If my math is correct, that means it takes 3.3 calories to heat up one ounce of ice(at 0°) to body temperature.
Now the question is: just how much ice can someone eat in a day? Remember, to lose one pound of weight you'll need to burn 3500 calories.