What is the basis for recommending eight cups of water a day

davidfilmer

It seems that everybody knows that we are supposed to drink eight cups of water a day, but nobody seems to know where that number comes from (why not six? why not ten?)

Can anyone here cite an authoritative source which established this number?

Thanks!

xdannigirl

generally you take your weight and divide that by two...that's how many ounces you're supposed to drink. i guess 8 was just a central number?

SuperHeroRipped

"Replacement approach. The average urine output for adults is about 1.5 liters (6.3 cups) a day. You lose close to an additional liter (about 4 cups) of water a day through breathing, sweating and bowel movements. Food usually accounts for 20 percent of your total fluid intake, so if you consume 2 liters of water or other beverages a day (a little more than 8 cups) along with your normal diet, you will typically replace your lost fluids.

Eight 8-ounce glasses of water a day. Another approach to water intake is the "8 x 8 rule" — drink eight 8-ounce glasses of water a day (about 1.9 liters). The rule could also be stated, "Drink eight 8-ounce glasses of fluid a day," as all fluids count toward the daily total. Although the approach really isn't supported by scientific evidence, many people use this easy-to-remember rule as a guideline for how much water and other fluids to drink.

Dietary recommendations. The Institute of Medicine advises that men consume roughly 3 liters (about 13 cups) of total beverages a day and women consume 2.2 liters (about 9 cups) of total beverages a day." -Mayo Clinic
http://www.mayoclinic.com/health/water/NU00283

Amo_Angelus

becaue it's the minimum number of cups a healthy, slender, short adult hould be drinking and therefore applies to everyone else as a starting number.

meokk

http://www.mayoclinic.com/health/water/NU00283

dittiepe

Way back when, the nutritional and medical society rounded and averaged. Your bp should be 120/80, your temperature 98.6, you should drink 8 8oz glasses of water/day. And then reality set in and they realized that not everyone was a cut-out cookie. So you should now have your bp within a range, your temperature should be between 97 and 99 and you should calculate your water intake based upon your weight and activity.

Icewolf_The

Thanks Max.. never had anyone describe it for me quite so well or clearly!! Is there any fluctuation based on body size? I ask because you stated that men should drink more and men typically have a bigger body composition. Well... I have more than that So at my current weight (400.2) should I be consuming 12? 14? etc... Thanks!!

ps: I ADORE the MayoClinic website myself - cynthia