I normally drink about 2 L of ice water at work. Someone brought this up to me and looking at the simple math it seems that it could be true.
1 Cal = 1000 cal
1 cal = 1 degree C/g of water
1 L water = 1 kg = 1000 g
Ice water is approx 0 C
Body temp is approx 37 C
So doing the math of warming 1000 grams of water 37 degrees
1000*37 = 37000 cal = 37 Cal. Then again is it possible that your body doesn't heat it all the way and just passes the cold water?
Admitedly that isn't a whole lot but over the course of a year I guess it would add up somewhat.