A calorie is the amount of energy required to raise 1 milliliter of water 1 degree Celsius.<\/p>\n
A food calorie is really 1000 calories, or a kilocalorie.<\/p>\n
Therefore a food calorie is the amount of energy required to raise 1 liter of water 1 degree Celsius.<\/p>\n
Body temperature is 37C (98.6F)<\/p>\n
If you drink cold beer, your body must expend energy to raise the beer from its temperature at intake to body temperature.<\/p>\n
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For example, just to make the math simple, let’s say you drink half a liter of beer (about a pint) which you pulled out of the 4C refrigerator, you would burn 0.5 food calories per degree, or about 16.5 food calories:<\/p>\n
Starting temp: 4C\r\nEnding temp: 37C\r\nDelta: 37-4 = 33C\r\n\r\nVolume: 0.5L\r\nEnergy: 33 * 0.5 = 16.5 kcal<\/pre>\nGiven that your average American lager beer has about 12 (food) calories per ounce, we can extrapolate by volume, and then calculate net savings for a range of temperatures.<\/p>\n