Why We Should All Drink Less Water and More Coffee

If you believe some people, I should have shriveled up long ago.

That’s because instead of drinking the supposedly necessary 8 glasses of water per day, I probably drink one or two, if that. On top of that, I drink at least four cups of coffee and I used to drink a couple glasses of soda, as well. According to the water-obsessed, not only does the water in coffee and soda not “count”, but it also dehydrates you – basically, it works like “negative water”. So if you add it all up, I must be getting a bit more dried up every day, and should probably be dead by now.

I always wondered whether the 8 glasses a day rule was some kind of myth, perhaps fueled by the multi-billion dollar bottled water industry. Recently, when embarking on my quest to lose a tiny bit of weight, I had the chance to do some research. That’s because all the weight loss information you can find anywhere urges you to increase your water intake. Some sources suggest not 8 glasses, but something more like 12-16 glasses a day. The idea is that not only is all this extra water somehow “good for you” (though nobody ever seems to explain how exactly), but also magically “melts away” or “flushes away” or “dissolves” fats and “toxins”. Weight loss gurus also claim that drinking extra water can make you feel fuller – for example, you are supposed to drink a full glass before sitting down to a meal, hopefully to ensure that you eat a bit less. This last factoid I could sort of get behind (it didn’t sound so pseudoscientific as the others), so I did make a bit of an effort to increase my water intake up to around 6-8 glasses per day.

It didn’t seem to make me feel any fuller, but it did make me pee constantly, which was pretty irritating. So I figured maybe I should look into this water thing a bit more.

Here’s what I found out: there is no reason that a healthy person should ever drink 8 or more glasses of water per day. Most people can drink perfectly adequate amounts of water by just letting their thirst guide them. In fact, the larger ranges of suggested water consumption (14 glasses or more) can be a bit dangerous for some people, because it puts stress on the kidneys and forces them to output huge quantities of dilute urine. Another potential danger is the increasing amounts of toxins in our water supply – not a big deal for most people drinking a reasonable amount of water, but if a lot of the populace is drinking 14+ glasses of water per day, one might wonder whether things like cancer rates could show an increase on average.

It turns out that the myth of 8 glasses of water per day came from an old, misinterpreted report (you can read about it here) that stated that most people need the equivalent of 8 glasses per day from all food and drink they consume. Most of this water, in fact, probably comes from our food intake (yes, food has a lot of water in it!). The remainder can come from plain water, flavored drinks, coffee, tea, soda, or whatever else you like. In actuality, caffeine-containing drinks do not significantly dehydrate the body (you can read about it in this recent NYT article).

There is no evidence that water “flushes out” or “melts” anything in our body, including fat or woo-woo “toxins”. There is also no mechanism by which this kind of “melting” action could possibly occur. Finally, the theory that I briefly ascribed to – that water might “fill you up” is also pretty suspect. Food scientists think that the human body is actually not capable of interpreting water consumption as “filling” (for sound evolutionary reasons). However, when extra water is mixed with our food (such as in soup), we can interpret water consumption as filling to some degree (I love soup, so this is good news!).

Although chugging extra water excessively is not really a great idea, it turns out that our liquid consumption can have a significant impact on weight in terms of the kinds of liquids we choose to consume. Drinking a couple of glasses of soda for example, adds a ton of calories to the diet. Even healthy beverages like milk or juice, if consumed in any significant quantities, are a pretty bad dietary decision, if you think about it. Add to this the fact that our bodies don’t really feel “full” after drinking these calorific drinks, and you could easily increase your calorie consumption by 1/10 to 1/3 per day without even noticing it.

So the moral of the story? Drink more coffee – it has only two calories per cup, contains tons of antioxidants, and is non-dehydrating!

Sources:

http://www.snopes.com/medical/myths/8glasses.asp
http://www.nytimes.com/2008/03/04/health/nutrition/04real.html?_r=2 scp;=1 sq;=dehydration st;=nyt oref;=slogin oref;=slogin
http://www.usatoday.com/news/health/2007-03-25-soda-drinkers_N.htm
http://ajpregu.physiology.org/cgi/content/full/283/5/R993

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