CLOSE
ThinkStock
ThinkStock

Where Did the 8 Glasses of Water A Day Myth Come From?

ThinkStock
ThinkStock

By Chris Gayomali

We have all been told at some point that proper hydration requires us to consume eight glasses of water a day. That works out to about two liters, which is an awful lot of fluid, considering the average human stomach (when unexpanded) is about the size of a balled fist.

But health researchers have refuted the eight-glasses-a-day claim as a silly myth riding a wave of flimsy scientific literature. In fact, many of the groups behind the public push for over-hydration have been exposed as having — surprise! — monetary interests in the fluid industry.

For example: In a 2011 article published in the British Medical Journal, Margaret McCartney debunked the eight glasses a day myth and noted that one water advocacy group in Europe, Hydration for Health, is not only sponsored by, but was actually created by food giant Danone. Under the company's expansive culinary umbrella? Volvic, Evian, and Badoit bottled waters.

Set aside the entangled interests of Big Bottled Water, and you'll see that study after study continues to show that the human body is remarkably resilient when it comes to quenching our thirst. Saharan nomads, for example, are capable of subsisting on very little water for days at a time in one of Earth's most hellish climates, as was first noted in 1976 by anthropologist Claude Paque.

You and I, on the other hand, may get a bit cranky in our air-conditioned offices if we forget to visit the water cooler for a morning, but it's highly, highly, highly improbable that we'd shrivel and die at the dusty hands of the dehydration monster. Consider all the other stuff we consume. Despite the widely held notion that tea and coffee dehydrate us, they actually count toward our overall water intake, says Dr. Stanley Goldfarb, a nephrologist (kidney researcher) at the University of Pennsylvania. Even though we're told it's important to drink eight glasses of water a day, "there's no evidence that benefits health in any real way and it really represents an urban myth," says Goldfarb. Even something like, say, a baked potato, is 75 percent water.

So where exactly did this eight glasses of water a day voodoo come from? The very idea of a "minimal water requirement" is actually a fairly recent notion that 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 [2.5 liter] of fluid should be ingested on a daily basis," although a primary clinical study was never actually cited.

The idea may have been at least partly put forth by Frederick J. Stare, an influential 20th century nutritionist and founding chairman of the department of nutrition at the Harvard School of Public Health. (He passed away in 2002 at age 91.) Stare was one of the first to recommend that humans consume six or so 12-ounce glasses of water a day.

Since then, researchers have begun to see eight glasses a day as an overestimate (especially considering our diets), but there are still advocates pushing for eight glasses of pure water or more. Those proponents include Dr. Fereydoon Batmanghelidi, a medical practitioner in Virginia who claims that a lack of water is responsible for many preventable diseases. Water, after all, is still good for us. Recent studies have suggested that adequate hydration may not only give our cognition a boost, but goes a long way toward keeping chronic kidney disease at bay.

As for how much we should be drinking, there is unfortunately no hard and fast rule. (Sorry!) And when you include all the other stuff we munch on or guzzle throughout the day, we actually consume more than the recommended two liters. A 1995 Australian survey found that the diet of average adults provides more than enough daily fluid: Women take in about 2.8 liters a day, and men consume 3.4 liters a day.

Research suggests that drinking water when you start to feel thirsty is sufficient should you desire to continue existing. Clearly, it's all relative, as when you feel thirsty will be different if you're drenching yourself in spin class or spinning in your cushy chair at work. As with most things, it's probably best to listen to your body before proceeding accordingly.

More from The Week...

A Linguistic Dissection of our Affect/Effect Problem

*

12 Things We Know About How the Brain Works

*

Silence is Golden. It Can Also Drive You Crazy

nextArticle.image_alt|e
WANG ZHAO/AFP/Getty Images
arrow
Big Questions
What Are Curlers Yelling About?
WANG ZHAO/AFP/Getty Images
WANG ZHAO/AFP/Getty Images

Curling is a sport that prides itself on civility—in fact, one of its key tenets is known as the “Spirit of Curling,” a term that illustrates the respect that the athletes have for both their own teammates and their opponents. But if you’re one of the millions of people who get absorbed by the sport once every four years, you probably noticed one quirk that is decidedly uncivilized: the yelling.

Watch any curling match and you’ll hear skips—or captains—on both sides barking and shouting as the 42-pound stone rumbles down the ice. This isn’t trash talk; it’s strategy. And, of course, curlers have their own jargon, so while their screams won’t make a whole lot of sense to the uninitiated, they could decide whether or not a team will have a spot on the podium once these Olympics are over.

For instance, when you hear a skip shouting “Whoa!” it means he or she needs their teammates to stop sweeping. Shouting “Hard!” means the others need to start sweeping faster. If that’s still not getting the job done, yelling “Hurry hard!” will likely drive the point home: pick up the intensity and sweep with downward pressure. A "Clean!" yell means put a brush on the ice but apply no pressure. This will clear the ice so the stone can glide more easily.

There's no regulation for the shouts, though—curler Erika Brown says she shouts “Right off!” and “Whoa!” to get her teammates to stop sweeping. And when it's time for the team to start sweeping, you might hear "Yes!" or "Sweep!" or "Get on it!" The actual terminology isn't as important as how the phrase is shouted. Curling is a sport predicated on feel, and it’s often the volume and urgency in the skip’s voice (and what shade of red they’re turning) that’s the most important aspect of the shouting.

If you need any more reason to make curling your favorite winter sport, once all that yelling is over and a winner is declared, it's not uncommon for both teams to go out for a round of drinks afterwards (with the winners picking up the tab, obviously). Find out how you can pick up a brush and learn the ins and outs of curling with our beginner's guide.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

nextArticle.image_alt|e
iStock
arrow
travel
Why You Should Never Take Your Shoes Off On an Airplane
iStock
iStock

What should be worn during takeoff?

Tony Luna:

If you are a frequent flyer, you may often notice that some passengers like to kick off their shoes the moment they've settled down into their seats.

As an ex-flight attendant, I'm here to tell you that it is a dangerous thing to do. Why?

Besides stinking up the whole cabin, footwear is essential during an airplane emergency, even though it is not part of the flight safety information.

During an emergency, all sorts of debris and unpleasant ground surfaces will block your way toward the exit, as well as outside the aircraft. If your feet aren't properly covered, you'll have a hard time making your way to safety.

Imagine destroying your bare feet as you run down the aisle covered with broken glass, fires, and metal shards. Kind of like John McClane in Die Hard, but worse. Ouch!

Bruce Willis stars in 'Die Hard' (1988)
20th Century Fox Home Entertainment

A mere couple of seconds delay during an emergency evacuation can be a matter of life and death, especially in an enclosed environment. Not to mention the entire aircraft will likely be engulfed in panic and chaos.

So, the next time you go on a plane trip, please keep your shoes on during takeoff, even if it is uncomfortable.

You can slip on a pair of bathroom slippers if you really need to let your toes breathe. They're pretty useless in a real emergency evacuation, but at least they're better than going barefoot.

This post originally appeared on Quora. Click here to view.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios