[LessEveryDay]

First, let me declare that I'm not obsessive! I'm just curious! I'm reading a physics book by Feynman for fun right now. Yesterday, I finished Freakonomics.

In the winter, I tend to drink my tap water at room temperature, switching to colder water as it gets warmer. It occurred to me that all the water that leaves my body, no matter the route, is me-temperature (37º C). So, my body used calories to warm it up along the way. So, I did some math.

The water to fill my 32 ounce water bottle weighs about two pounds or 907 grams. It takes one calorie to raise one gram of water one degree Celcius. My fridge water dispenser is about 4ºC, so my body must raise the water by 33ºC. That's 907 x 33 = 29,931. Sounds fantastic (except that we'd all probably starve to death!) until you take into account the fact that food calories are actually kilocalories (kCal). So, you have to divide that number by 1,000 to arrive at the "calories" you see on the nutrition label. That means just about 30 calories are burned to get my fridge-cold 32 ounces of water to body temperature. To warm up my room temperature water is about half that.

So, I'll burn an extra 15 calories if I use fridge water instead of warmish tap water. As I probably drink this thing three times per day, that's 45 calories extra - or one pound in three months. I think I'll just keep drinking it at the temperature I feel like!

[starchild]

It's amazing that you've tapped into the science of this! I recently switched to drinking ice cold water after reading that it serves as a metabolism booster. What you've come up with sounds in line with what I read.

[Iianae]

Im impressed!!

[LBH]

That's hilarious!!

[Circebee]

How cool! I love hearing about the science behind how our bodies function, and love it when other bio-geeks strut their knowlege! Hmmm- maybe sucking ice cubes are the answer to snacky cravings- cool AND calorie buring, how useful.....

[poppyseeds]

How many calories will I burn eating ice cold ice cream??? ROFLMAO!!!

... just kidding!

I always drink ice water in my 32 oz bottle so I'm good to go already!!

[LessEveryDay]

I hadn't thought about ice cream! Does that mean I get a 30 calorie discount on the ice cream's calories? Oh, wait, I'd have to eat 32 ounces! (Well, the ice cream would be colder, but still!)

[kaplods]

In a college human biology class this subject came up (that and the negative calorie vegetable theory) and the professor claimed that the calculation isn't that simple, because the cold water actually alters the body's biochemical functions (metabolism, etc). He argued that it has been calculated that a quart of ice water has only a couple negative calories, because the cold ice water actually slows metabolism slightly, or some such. He said that human metabolism can't really be compared to a furnace, because extra energy is also expended in "cooling down" the body. So eating very hot foods would also require extra work (calories burned) for the body. So, in some ways that drinking the cold water is like "turning down" your furnace you have to take into account the decrease in efficiency.

I don't remember all of the biochemical reactions that he were involved (I remember him filling up three chalkboards in the lecture hall).

So, ultimately I think that the difference is so small that a person should drink their water at the temperature they like it best (for me, that's VERY, VERY cold, so the extra calorie or two is bonus).