8 Glasses of Water A Day: Truth, Myth, or Scam?
By Jay Wiener
Should you drink 8 glasses of water every day? It’s great advice, but only if you’re a flounder. If you’re human, it’s a silly health myth that refuses to die. Regardless, dieters obey it like an eleventh commandment: “Thou must drinketh water until thou waketh three times nightly to pee.”
Not long ago, I watched Dr. Sanjay Gupta interview some muscular lunk about a diet book he had ‘written’ in which he shows ‘The Best Way To Lose Weight Very Quickly’. (Note: the old ‘Lose Weight Quickly” meme is a great way to sell pallet-loads of diet books while helping absolutely no one.) In the interview, Mr. Lunk (that may not be his real name) promoted his theory: people must drink a large glass of water before every meal, and they must drink a great deal more water throughout the day to stay hydrated. To him, 8 glasses of water every day was an absolute minimum.
It’s a wonderful suggestion if you are riding a camel in a caravan of desert nomads, but not if you are living in, say, Seattle.
Are We All Dehydrated?
Sanjay Gupta is one of the smartest media docs we have. He earned his gravitas legitimately, but during the segment on drinking more water, he said, “We walk around, in our society, chronically dehydrated.” Excuse me? You don’t need to be a zoologist to know that if there are abundant, safe supplies of water, it is impossible to keep a large group of intelligent mammals dehydrated for more than ten minutes. Evolution weeded out our thirst-ignoring ancestors during The Cambrian Period. And yet, authorities everywhere keep claiming that we do not drink enough water, based on absolutely no evidence at all.
So who created the eight-glasses-of-water-a-day shibboleth? According to Chris Gayomali, in a smart article he wrote for This Week, “The very idea of a “minimal water requirement” is fairly new; it first appeared in dietary guidelines published in 1945 by the Food and Nutrition Board of the National Academy of Sciences. The academy spuriously suggested that ‘2,500 mL [2.6 quarts] of fluid should be ingested on a daily basis,’ although a primary clinical study was never actually cited.” Translation: someone was guessing.
Should You Drink 8 Glasses of Water Every Day?
In a word, no. Regardless, the myth lingers on, kept alive by organizations such as Hydration for Health. Their advice for health professionals is simple, direct, and has been repeated around the world: “Recommending 1.5 to 2 (quarts) of water daily is the simplest and healthiest hydration advice you can give.” However, according to the British Medical Journal, “Hydration for Health has a vested interest: it is sponsored by and was created by French food giant Danone, a major producer of bottled water (Evian, etc.)
The people who gush with effervescent praise over the glories of drinking 8 bottles of water every day are the people who sell us bottled water.
And what about the studies saying that hydration is essential for health? Either they were misquoted or they were bad studies. Again from the BMJ, “In 2002, Heinz Valtin published a critique of the evidence in the American Journal of Physiology. He concluded that “Not only is there no scientific evidence that we need to drink that much, but the recommendation could be harmful… ” From the June, 2008 Journal of the American Society of Nephrology “There is no clear evidence of benefit from drinking increased amounts of water… There is also no clear evidence of lack of benefit. In fact, there is simply a lack of evidence in general.” (2008)
Blame Dannon (and a Few Others)
Giant bottled water marketer Danone has taken a popular old myth and turned it into a hugely profitable scam. (FYI, Danone is better known in the US as the maker of Dannon Yogurt.)
However, if you are studying for finals in a cool, dark college library, drinking all that water is a terrible idea. At best, you will spend half the day walking back and forth to the toilet. At worst, you will end up in the hospital with water intoxication. That’s even less fun than studying for finals in a dark college library.
Obviously, drinking water instead of fruit juice or sugary soda is smart; soda labels should have a skull and crossbones on them. However, boosting liquid intake for its own sake is useless. It will help improve a few bottom lines; it will not improve your health. On the other hand, despite the widely held notion that tea and coffee dehydrate us, they do not. The minor diuretic effect of caffeine is overwhelmed by the sheer volume of water in a cup of coffee, so if you want to waste your money on a $7 double almond latte at Starbucks, don’t feel guilty. About the caffeine.
What is the Best Way to Stay Hydrated?
Very simple: don’t let yourself get thirsty. Drink some water, tea, or coffee before you do, especially on hot days or if you are exercising. And stop stressing over all the rules you are told to follow, including this one.
If you think about it, asking everyone to drink eight glasses of water a day doesn’t make any sense. Why should a 5-foot tall grandmother need to drink the same amount of water as her grandson, the 6-foot tall college football player? Why are 8 glasses of water every day perfect but not seven or nine? And why is this silly myth still floating about the Internet like a dead flounder?
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