I learned this morning that you can burn calories simply by drinking water. After thinking about it, it makes a lot of sense.
I figured out you can burn up to 137kcal just by chilling your drinking water to just over freezing.
The human body has a maintained internal temperature of 37°C. When you drink water, the water cools the body down, so the body reacts by heating back up (thermogenesis) so it can remain at 37°C, which involves burning calories.
So how many calories are burned? That depends on the amount and temperature of the water you drink.
The formula to determine the calories used is actually very easy, because the definition of a calorie is “the energy needed to raise the temperature of 1 gram of water through 1°C”. Note that “calorie” in this case is 1/1000th of a kcal, which is what people usually call a calorie. Yeah, humans, confusing things aren’t they. Personally, I use kcal as the main measure, and if I say “calorie”, I mean “one thousandth of a kilo-calorie”.
Assuming that tap water is at room temperature (about 20°C), it would therefore take 17 calories per mililitre (1g of water equals 1ml of water) to heat it to body temperature, or 17kcal per litre.
So if you drink a standard-sized glass of water (240ml), this will burn 4080 calories (240ml*17°C), or about 4kcal.
To double the amount of calories burned, cool the water to just above freezing. This way a glass of water will burn 9kcal (.240l*37°C = 8.88kcal).
The recommended daily intake of water is 3.7 litres for a male, or 2.7 litres for a female.
So, it is possible to burn 137kcal per day (3.7*37°C = 136.9kcal) just by chilling all of your water.