Should your eight glasses be half-full?
Image: bfurnace via Flickr
More In This Article
-
Overview
More Fact or Fiction Columns
-
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
Virtually every health-conscious person can quote the recommendation: Drink at least eight eight-ounce glasses of water per day. Other beverages—coffee, tea, soda, beer, even orange juice—don't count. Watermelon? Not a chance.
There's no denying that water is good for you, but does everyone really need to drink 64 ounces or more every day? According to Heinz Valtin, a retired professor of physiology from Dartmouth Medical School who specialized in kidney research and spent 45 years studying the biological system that keeps the water in our bodies in balance, the answer is no.
Valtin says that for people who have specific health concerns, such as kidney stones or a tendency to develop urinary tract infections, drinking lots of water can be beneficial. But after an extensive search in 2002 for the origins of what is commonly referred to as the "8 x 8" guideline and a review of associated health claims, he reports finding no scientific evidence supporting the notion that healthy individuals need to consume large quantities of water. In 2008 Dan Negoianu and Stanley Goldfarb reviewed the evidence for the Journal of the American Society of Nephrology. They came to a similar conclusion: "There is no clear evidence of benefit from drinking increased amounts of water."
In fact, Valtin found that the 8 x 8 guideline may have originated from a misunderstanding. In 1945 the Food and Nutrition Board, now part of the National Academy of Sciences's Institute of Medicine, suggested that a person consume one milliliter of water (about one fifth of a teaspoon) for each calorie of food. The math is pretty simple: A daily diet of around 1,900 calories would dictate the consumption of 1,900 milliliters of water, an amount remarkably close to 64 ounces. But many dieticians and other people failed to notice a critical point: namely, that much of the daily need for water could be met by the water content found in food.
The Board revisited the question of water consumption in 2004. Its panel on "dietary preference intakes for electrolytes and water" noted that women who appear adequately hydrated consume about 91 ounces (2.7 liters) of water a day and men about 125 ounces (3.7 liters). These seemingly large quantities come from a variety of sources—including coffee, tea, milk, soda, juice, fruits, vegetables and other foods. Instead of recommending how much extra water a person should drink to maintain health, the panel simply concluded that "the vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide."
See what we're tweeting about
31 Comments
Add CommentThis is probably true for a number of "medical facts" assumed to be true but never subjected to the rigors of investigation. Medicine is still a complex mixture of anecdotes, experience and science.
Reply | Report Abuse | Link to thisJust as they don't want a rule for all water intake recommendations, they just made one for everyone, you don't have to worry about dehydration because your body will tell you when you have a problem. Well, I call BS. Having been a family practice doctor in Arizona for 17 years, once people get hot, they don't keep enough fluids in reserve. Most people are on the verge of dehydration our here and the risk for older people and young athletes is huge. Why do we have some many football deaths in the summer, they are driven and their bodies aren't telling them when they are getting into trouble which is why many schools have gone to mandatory drinking breaks during practice. As to drinking too much water, in 17 years of medical practice (and I say a lot of people), never have I seen a case of water intoxication from drinking too much. If your body can tell you that you are thirsty, it can also tell you it is not and your urge to drink will stop (all this doesn't apply to people taking medications). The researchers and experts seem to forgot that not being sick and being healthy aren't the same thing. Kidneys excrete bad stuff. Bad stuff has to be dissolved in urine, the more urine, the more bad stuff can be removed. 64 oz per day may be a bit much if you are in Maine, but inadequate even for someone in July in Phoenix even if they are indoors most of the day. I think the "drink until your urine is clear" method is perhaps the best was to approach this, but don't tell people in the southwest that their bodies will protect them, they just don't.
Reply | Report Abuse | Link to thisIt appears you may not have read "Water requirements depend so much on outside temperature" that is found in the second to last paragraph which would account for why your Arizona patients need more water when it is hot outside, which this article's reasoning does allow for.
Reply | Report Abuse | Link to this
Reply | Report Abuse | Link to thisDoes a 100 lb woman need the same 64 ozs of water as a 280 lb man? Does a sedentary office worker need the same 64 ozs as a construction worker who works outdoors?
The 8x8 advocates are parroting a simple minded action, that does not stand up to investigation and one size clearly does not fit all here.
The story line I have always heard regarding water and weight loss was thus: if a body is dehydrated then it retains water. If the 8x8 rule is followed then the body sheds extra water weight. Thus following 8x8 results in about 2 to 3 pounds of water weight that is shed. So, this is incorrect?
Reply | Report Abuse | Link to thisI developed a habit of drinking a lot of water while I was in the Air Force. I've been out for 2 years. Personally, I couldn't see the 8 x 8 rule as being some standard that would satisfy my body's need for water. I did notice, however, that my digestion improved and I just felt better. So, I concur with both sides of this argument, because if I never shot for the straining 8 x 8 rule then I would have never hit my halfway mark. But, for those of us that drink soda all day, you may want to give the 8 x 8 guidline a chance.
Reply | Report Abuse | Link to thisJust drink enough to stay hydrated. you will feel a lot better and when you get use to it, then go too high or low you will notice
Reply | Report Abuse | Link to thisThe key may be several fold. Is there fatigue for no obvious reason, i.e. Is lab work normal and is there any changed in urine or bowel habits. As stated earlier- this may not be a person who feels 'sick', but could possibly (note I said possibly) need more fluid ? every provider of Hlth care should be looking at the whole person- before making ANY kind of recommendations. Coffee as part of the fluid regimen may be fine if BP is normal & they don't smoke, for example; but maybe not if the pt. has fluid retention (kidney or cardiac) issues! 8 x 8 is still going to be on my list for patients to MAINTAIN health.
Reply | Report Abuse | Link to thisOne must consider foods eaten by the individual. Those that eat salty foods for better or worse need more water in compensation and those that lack sufficient potassium, many people in this category might need less or more, It is not a simple drink this and be healthy. My mother who is over 100 never did drink more than a sip here and there. She never once upended a glass of water. I on the other hand drink in hand most of the day. There is no one size fits all in this area. In desert areas I recall seeing people carry gallon jugs and swig it down and most evaporated as sweat. This water requirement is as unfounded as the avoid eggs due to its cholesterol...unfounded nutritional nonsense.
Reply | Report Abuse | Link to thisIt does seem that our sense of thirst is not a perfect guide to the optimal amount of water intake. I find that I can sometimes snap out of periods of fatique with nothing more than a couple of glasses of water. That being said, most of my liquid intake consists of coffee which, according to the most fundamental interpretation of the old 8x8 and coffee-as-a-net-dehydrater homilies would suggest I should have died forty years ago.
Reply | Report Abuse | Link to thiswater can ease constipation,lack of it can cause it.
Reply | Report Abuse | Link to thisI work an office job and I drink a lot of water (3 or 4 32 oz cups) through the day. Anytime I feel like I'm getting a headache, I know I'm dehydrated and literally it goes away within 10 minutes of drinking a bunch of water.
Reply | Report Abuse | Link to thisOnce you start drinking water all day, you quickly notice when you haven't had enough, and that may be a clue into the notion that people who don't drink very much liquids don't know when they are dehydrated.
Also, when I started drinking a lot of water, not flavored, I began to crave water, and find sodas and juice too sweet a lot of the time.
I just don't buy this argument. I lived in Antarctica for 14 months and that experience taught me a lot about the importance of water. I found I had to drink AT LEAST 3 liters of water a day - usually more. You learn the rule: "If you are thirsty, it's too late." People carry around Nalgenes full of water like baby blankets. It felt like sensitivity training for your body.
Reply | Report Abuse | Link to thisNow back in the "real world" I know right away when I haven't had enough water. Just as metalmonkey commented, I know when I am becoming dehydrated either with an oncoming headache or just feeling all-around wonky.
I remember first hearing about this a few months ago, but after my experience in Antarctica, I'm just not convinced and probably won't be on this one.
I have never been able to drink 8 glasses of water a day and feel comfortable. It always felt like forcing myself. I finally decided to follow the Ayurvedic wisdom of drinking only when thirsty. That is working for me -- I don't feel any worse or have any health problems from drinking less.
Reply | Report Abuse | Link to thisIt seems like Western science leans towards "one size fits all" with its recommendations. People's physiologies are so vastly different. I feel we need to learn more about different types of people and what they need in terms of food, drink, exercise, sleep, etc. Also, I feel its essential that people start to pay attention and listen to the signals they receive from their own bodies. We have so much lost touch with the "instinctual".
What about the "water cure"?
Reply | Report Abuse | Link to thisI think you are absolutely right. People/ writers should not be allowed to publish public health care related articles until they are cunsulted by the health care professionals. Too many times do I read articles that are questionable at best.
Reply | Report Abuse | Link to thisIt is not correct to let thirst be your guide. At higher altitudes, in hill places where I have lived, low pressures increases evaporation without sweating and little or no thirst is felt. Not consuming enough water gave me sleepless nights until I forced myself to drink enough each day.
Reply | Report Abuse | Link to thisMaybe one can get used to large quantities of water and therefore more sensitive to the lack thereof.
Reply | Report Abuse | Link to thisDuring activity, your bodies need for water can likely outpace the ability for it to tell you its thristy and you may not be paying attention if you are engaged in sport or other exciting activity. That is likely why people run into trouble. but, that doesn't mean you need to mindlessly drink water in normal situations.
Anyway, why don't people just do what makes them feel best. Regardless of what people say, I feel bloated adn sick if I drink per the 8x8 "rule" so I don't. Other feel better drinking more, so go ahead an do that. Why do you need a study for this.
Best advice--drink until you have to pee at least every 2-3 hours while up during the day. If you sweat like I do, that's a fair amount of fluids. Some people don't sweat like that-so don't drink as much. If you are outside working and sweat like me--it can be hard to keep up. You have to learn what your body needs and adjust.
Reply | Report Abuse | Link to thisThe other part of drinking lots of water in hot weather is often electrolyte loss from sweating out the electrolytes. That includes loss of iodine which can lead to fatigue from a drop in thyroid function. I've had a lot of personal experience with prolonged sweating having worked many years in a Southern California fire department and since, also living for 9 years in Vietnam.
Reply | Report Abuse | Link to thisDrinking more water may help some, but there is a need to take in electrolytes so watery fruits, vegetables and especially coconut water helps. Also Pho (noodle soup) that contains lots of herbs and leafy vegetables; and possibly electrolyte drinks but I have never found any that I liked, they were too expensive and not as good as coconut water. There are some powdered electrolyte supplements, oral electrolyte replacement salts, that are used in treating cholera. Other supplements can be found in vitamin shops. Some supplements are good but others are very weak. The price and amount of ingredients varies widely so read labels carefully.
Some of the symptoms of electrolyte loss that I notice are restless sleep and shakiness, then the worst is being extremely easy to anger. When I notice myself having angry thoughts about little things I take some electrolytes and the thoughts go away. Others have the same effect. One man I met was a teacher in Vietnam for 5 years and said he was planning to leave because he just wasnt himself, very grouchy and irritable. I gave him a packet of electrolyte replacement powder and he said taking it returned him to his normal self.
I wonder how much of the unfortunate abusing and killing of civilians during wars in Iraq and years before in Vietnam could have been reduced with the better use and knowledge of electrolyte supplements. Yes, there is such a thing as low electrolyte rage. Combined with the emotional pressures of war and extreme fatigue you end up with a very short fuse.
Not true....I know someone who drinks vodka...they said this Love the vodka and the bottle looks great, Joel Madden said. Roberto Cavalli Vodka unveiled its summer recipe collection June at a grand opening for Soffer Ari USA hosted by celebrity DJ Joel Madden from rock band Good Charlotte and Catt Sadler of E! Entertainments hit show The Daily 10 . Celebrity guests also included Roberto Cavalli Vodka endorsed rock artist Merlinmoon, Backstreet Boys AJ McLean, and fashion designer Lisa Kline.
Reply | Report Abuse | Link to thisThank goodness! I've always know this was true, but got tired of arguing with the eight glasses people.
Reply | Report Abuse | Link to thisThank goodness for articles like this one! I have never agreed with the "8 glasses" people. Just logically, the water in coffee and soda (which I don't drink) and watermelon and lettuce have to count. As someone who lives in a hot dry climate, and has to drive to get anywhere...I couldn't leave the house if I drank 8 glasses of water a day...I'd need a portable potty.
Reply | Report Abuse | Link to thisAfter reading all the comments it seems like an individual thing. If you have to force yourself to drink 8x8 then you probably don't need it.
Reply | Report Abuse | Link to thisThis sounds like everything else: eat butter, no eat margarine. Eggs are bad, no.. they're ok. Don't eat beef - errr... it's ok to eat beef. I say DRINK LOTS OF WATER!
Reply | Report Abuse | Link to thisI love to stay hydrated and understand how important it is. I use an iPhone app called "Absorb Water" to help me everyday. What I really like about using this app is it allows me to eat an apple or drink a bowl of soup and the count towards my goal of 12 + glasses of water each day.
Reply | Report Abuse | Link to thisI love to stay hydrated and understand how important it is. I use an iPhone app called "Absorb Water" to help me everyday. What I really like about using this app is it allows me to eat an apple or drink a bowl of soup and the count towards my goal of 12 + glasses of water each day.
Reply | Report Abuse | Link to thisI don't understand. So, what you're saying is that people can't listen to their body to start drinking but they can listen to it to stop? That's flawed logic.
Reply | Report Abuse | Link to thisAnd you say kidneys excrete bad stuff which is totally true. What's technically not true is that they work on a "more urine, more bad stuff" mechanism because anything beyond optimal urine flow is just as bad as poor urine flow and dehydration. So, while drinking low amounts of water are obviously detrimental, your argument doesn't prove that drinking anything more than the right amount of water is beneficial. "Drink[ing] until your urine is clear" is also a poor indicator of health. While simply changes in the colour of your urine are important, dilution can only mean overhydration (save pathogenesis).
One last note. Schools implementing mandatory water breaks is an excellent idea. I think the problem with young athletes is not that their body doesn't tell them they're thirsty but more that they don't listen to the signs and instead "push through it". Taking breaks addresses that problem.
I agree with this article. I have read a lot of articles saying that it is advisable to drink 8 glasses or more a day. But don't overdo it to protect your kidneys.
Reply | Report Abuse | Link to thishttp://www.server-support-company.com/
As a physician, I actually tend to see more problems from people drinking too much water than too little. Low blood sodium due to excess water intake can be a life-threatening problem, leading to confusion, seizures, and death. Usually you have to drink a whole lot to cause this, but in cases of certain hormonal imbalances (e.g., Syndrome of Inappropriate ADH) even a small amount of excess water intake can be very harmful. I've had many elderly patients with this syndrome come into the hospital with very low sodium levels, telling me "I drink 8 glasses of water a day like they say to." Whoops! I like the "thirst as your guide' philosophy in MOST instances for this reason.
Reply | Report Abuse | Link to thishttp://ZDoggMD.com
water dont have a shadow thats vodka
Reply | Report Abuse | Link to this