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- - How much water? (https://thetfp.com/tfp/tilted-life/110170-how-much-water.html)

Sorry if this has been asked before, it seems like it should have but I couldn't find any threads about it. How much water per day does the average human body need? I've heard the 8 x 8 (8 cups of 8 oz) but I've also heard we don't need nearly that much. Case in point:

Quote:

Hanover, NH -- It has become accepted wisdom: "Drink at least eight glasses of water a day!" Not necessarily, says a DMS physician Heinz Valtin, MD. The universal advice that has made guzzling water a national pastime is more urban myth than medical dogma and appears to lack scientific proof, he found.

In an invited review published online by the American Journal of Physiology August 8, Valtin, professor emeritus of physiology at Dartmouth Medical School, reports no supporting evidence to back this popular counsel, commonly known as "8 x 8" (for eight, eight-ounce glasses). The review will also appear in a later issue of the journal.

Valtin, a kidney specialist and author of two widely used textbooks on the kidney and water balance, sought to find the origin of this dictum and to examine the scientific evidence, if any, that might support it. He observes that we see the exhortation everywhere: from health writers, nutritionists, even physicians. Valtin doubts its validity. Indeed, he finds it, "difficult to believe that evolution left us with a chronic water deficit that needs to be compensated by forcing a high fluid intake."

The 8 x 8 rule is slavishly followed. Everywhere, people carry bottles of water, constantly sipping from them; it is acceptable to drink water anywhere, anytime. A pamphlet distributed at one southern California university even counsels its students to "carry a water bottle with you. Drink often while sitting in class..."

How did the obsession start? Is there any scientific evidence that supports the recommendation? Does the habit promote good health? Might it be harmful?

Valtin thinks the notion may have started when the Food and Nutrition Board of the National Research Council recommended approximately "1 milliliter of water for each calorie of food," which would amount to roughly two to two-and-a-half quarts per day (64 to 80 ounces). Although in its next sentence, the Board stated "most of this quantity is contained in prepared foods," that last sentence may have been missed, so that the recommendation was erroneously interpreted as how much water one should drink each day.

He found no scientific studies in support of 8 x 8. Rather, surveys of fluid intake on healthy adults of both genders, published as peer-reviewed documents, strongly suggest that such large amounts are not needed. His conclusion is supported by published studies showing that caffeinated drinks, such as most coffee, tea and soft drinks, may indeed be counted toward the daily total. He also points to the quantity of published experiments that attest to the capability of the human body for maintaining proper water balance.

Valtin emphasizes that his conclusion is limited to healthy adults in a temperate climate leading a largely sedentary existence -- precisely, he points out, the population and conditions that the "at least" in 8 x 8 refers to. At the same time, he stresses that large intakes of fluid, equal to and greater than 8 x 8, are advisable for the treatment or prevention of some diseases, such as kidney stones, as well as under special circumstances, such as strenuous physical activity, long airplane flights or hot weather. But barring those exceptions, he concludes that we are currently drinking enough and possibly even more than enough.

Despite the dearth of compelling evidence, then, What's the harm? "The fact is that, potentially, there is harm even in water," explains Valtin. Even modest increases in fluid intake can result in "water intoxication" if one's kidneys are unable to excrete enough water (urine). Such instances are not unheard of, and they have led to mental confusion and even death in athletes, in teenagers after ingesting the recreational drug Ecstasy, and in ordinary patients.

And he lists other disadvantages of a high water intake: (a) possible exposure to pollutants, especially if sustained over many years; (b) frequent urination, which can be both inconvenient and embarrassing; (c) expense, for those who satisfy the 8 x 8 requirements with bottled water; and (d) feelings of guilt for not achieving 8 x 8.

Other claims discredited by scientific evidence that Valtin discusses include:

Thirst Is Too Late. It is often stated that by the time people are thirsty, they are already dehydrated. On the contrary, thirst begins when the concentration of blood (an accurate indicator of our state of hydration) has risen by less than two percent, whereas most experts would define dehydration as beginning when that concentration has risen by at least five percent.

Dark Urine Means Dehydration. At normal urinary volume and color, the concentration of the blood is within the normal range and nowhere near the values that are seen in meaningful dehydration. Therefore, the warning that dark urine reflects dehydration is alarmist and false in most instances.Is there scientific documentation that we do not need to drink "8 x 8"? There is highly suggestive evidence, says Valtin. First is the voluminous scientific literature on the efficacy of the osmoregulatory system that maintains water balance through the antidiuretic hormone and thirst. Second, published surveys document that the mean daily fluid intake of thousands of presumably healthy humans is less than the roughly two quarts prescribed by 8 x 8. Valtin argues that, in view of this evidence, the burden of proof that everyone needs 8 x 8 should fall on those who persist in advocating the high fluid intake without, apparently, citing any scientific support.

Finally, strong evidence now indicates that not all of the prescribed fluid need be in the form of water. Careful peer-reviewed experiments have shown that caffeinated drinks should indeed count toward the daily fluid intake in the vast majority of persons. To a lesser extent, the same probably can be said for dilute alcoholic beverages, such as beer, if taken in moderation.

"Thus, I have found no scientific proof that absolutely every person must 'drink at least eight glasses of water a day'," says Valtin. While there is some evidence that the risk of certain diseases can be lowered by high water intake, the quantities needed for this beneficial effect may be less than 8 x 8, and the recommendation can be limited to those particularly susceptible to the diseases in question.

http://www.sciencedaily.com/releases...0809071640.htm

So how much do you think we need? I've always drunk a lot, like 96 oz a day (sometimes more) not because I think its healthy but because I'm thirsty.

I think we need 8x8, however, I also believe that much of that 8x8 can come from what we eat.

One more vote for 64 oz as a minimum. An inexpensive water filter sure helps. I picked up an NSA Counter top setup for cheap on Ebay.

I think the answer may also depend on how much water you're losing, which has to do with levels of physical activity, among other things.

I have no idea how much water I drink everyday, but I'm sure it's a lot. I stop and take a drink at every water fountain I pass when I'm at school and I usually have a glass of water nearby when I'm at home. I do it to flush my system more than anything else.

-Tamerlain

Well yesterday I ended up drinking 120oz (15 cups) of water!

And for today, half the day has gone by so far and I've only drank ~24 oz.

I think I must have been flushing something out of my system yesterday.

Here are a few things I've run across over the years and added to my belief system:

- liquids are what counts but water doesn't need to be digested and doesn't contain diuretics (like caffeine) so I basically like water the best
- you need 2 ounces of water for every five minutes during your work out and are sweating
- the typical person drinks 64 ounces of fluid daily, which leads to Coke looking for share of stomache rather than market share and bases that on 64 ounces
- if you always pee clear you're probably drinking too much; it should be light yellow, not dark yellow which may mean you're not drinking enough or have a lot of vitamin B in your system

And I'm a firm beleiver in listening to your body! With that in mind, Zeraph, you probably did the right thing.

The research I've seen is that you should be drinking half your body weight in ounces a day.

The real test to know if you are drinking enough water is to check the color of your urine.. if it's anything but a very very light yellow to almost clear, you are dehydrated and should be drinking much more water. You'll feel a lot better

Did any of you actually read the article posted? Because most of what you're saying is in direct contradiction to the science presented in the article.

Vegetables and fruits are packed with water content, as are a lot of other foods. So if you're getting your five a day and also drinking an occasional cup of tea, juice, and some water, you're probably getting enough--if you're not exercising. Of course, when you exercise, you want to hydrate yourself. Otherwise, you really have no reason to drink that much water--unless you like peeing that much.

Personally, I get by on about 20 oz. of water a day on a day I don't exercise, in addition to tea, coffee, and the occasional soda. I've never seen any evidence as to me being dehydrated.

I drink when I find myself going "I'd like something to drink." I have heard that waiting until you're thirsty means you've waited too late and are already running too low on water, but I don't know if that's true.

I drink... oh... five to six glasses of water a day, plus some tea and the water I get from my food. I find that paying too much attention to any one detail of health and fitness is an easy way to get totally sidetracked from the main goal of having overall fitness- so I just do what feels right for me :)

Quote:

Originally Posted by Sage

The article says that there's no evidence that it is and a lot that it isn't.

Somthing related that I saw recently:

http://www.mirror.co.uk/yourlife/hea...name_page.html

Quote:

15 INSTANT ENERGY BOOSTERS
FEELING TIRED AND SLUGGISH NOW WINTER'S HERE? WELL HERE'S HOW TO PUT THE OOMPH BACK INTO YOUR DAY

...Guzzle water

WE all know how important it is to drink water, but studies show that even a two per cent drop in hydration can reduce energy levels by 20 per cent.

This is because insufficient water in your body causes a reduction in blood volume, which means that less oxygen reaches your muscles and you'll tire more quickly. Keep a bottle on your desk...

Now, of course, newspaper articles that say "studies show" but don't refer to any actual studies or researchers, much less quote them, are suspect in my book. But it does suggest that you might start to lose energy to a lack of water before you feel genuine thirst.

Quote:

Originally Posted by iccky

The article says that there's no evidence that it is and a lot that it isn't.

Somthing related that I saw recently:

http://www.mirror.co.uk/yourlife/hea...name_page.html

Now, of course, newspaper articles that say "studies show" but don't refer to any actual studies or researchers, much less quote them, are suspect in my book. But it does suggest that you might start to lose energy to a lack of water before you feel genuine thirst.

Well, and given that it's out of the Mirror--the UK's equivalent to the Enquirer--it's not the greatest source.

I'm sure I drink more than 8x8 a day. I'm just generally thirsty :).

If only I had a bigger bladder, I wouldn't have to go pee as much... :lol:

There are days when I don't drink any pure water at all, only 3-4 cups of tea. And I feel fine. When I exercise or work in high temperatures I do drink water, but 64 oz (~1.9 liters)? Nevah. And my pee is a nice light yellow, thank you very much.

I think when you drink so much water most of it goes straight through and takes important minerals and such with it on the way out, and I think you can get the body used to processing a lot of water, making you thirsty all the time, but it's not really healthy. Just my uneducated opinion.