Almost Everything You Know About Hydrating is Wrong

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From campaigns like “Is it In You?” to “Hydrate or Die”, we’ve all been taught by a multi-billion-dollar drinks industry that dehydration is deadly. What we haven’t been taught, because there’s no money in it, is that the best rule of thumb is only to drink when you’re thirsty.

That’s the conclusion of a scientific study just completed by Dr. James Winger of Loyola University Medical Center and several colleagues, who recently interviewed, weighed, poked, and prodded marathon runners to find out how they drank, when they drank, how much they drank — and what harmed or helped performance.

The critical takeaway: We all drink way too much water (and sports drinks), putting ourselves at risk of worse, not better athletic performance.

Yes, there’s lots of conventional wisdom around drinking, from the need to pound eight glasses of water a day to chugging a bottle an hour for cyclists. To which Dr. Winger responds: There’s no science behind those whatsoever. Zero. And the idea that you’re restoring electrolytes is absolute quackery, he says, because the amount of minerals and salts in these drinks is far too diluted to make a difference.

“The bottle an hour is just a convenient rule of thumb — in the past there have been calls to replace a liter of water for every kg of weight that you lose, but we know that even this can lead to overhydration,” Winger says.

And overhydration leads to reduced performance because your blood has to soak up some of the excess water in an attempt to equalize your body’s salinity. Then your cells begin to swell, causing all sorts of distress, from gastric to dizziness, soreness, and lots of other symptoms that do nothing to make you faster. In very severe instances you can wind up with major GI distress, vomiting, and the like. Go way overboard and there’s a risk of death, because cellular swelling in the brain — hyponatremia encephalopathy — can cause coma or worse.

Exercise-associated hyponatremia (EAS) isn’t rampant, but it’s far more common than symptoms of dehydration, and even mild forms will make you very uncomfortable.

A lot of what the study revealed is how popular media and advertising has skewed our perspective on hydration. The study points out that athletes now view dehydration as a “disease,” when it appears that our bodies are very well set up to perform slightly better when we’re somewhat dehydrated.

Here’s what else you should know:

LOSE WATER WEIGHT, GO FASTER.
“Fifty-five percent of our respondents indicated that drinking less correlates with a slower running performance. This is incorrect,” says Winger. “Marathon running, ultrarunning, triathlon, and cycling all show similar linear relationship between weight loss (which indicates less fluid intake) and performance (race time).” Dr. Winger points to a joint South African-French study that shows that mild dehydration, which is completely normal during exercise, corresponds to faster marathon event times across ages and skill sets.

SO I SHOULDN’T DRINK AT ALL?
Winger’s study doesn’t suggest abstaining from drinking during exercise, but concludes that if you drink when you’re thirsty rather than before, you’ll maintain perfectly adequate hydration. In fact, more experienced, and often faster runners in the study did just that and suffered much lower incidents of GI and other distress. Winger cautions that if it’s very hot, you should drink more but that your body will tell you this through thirst, and he says you cannot over-tax this mechanism. It’s ancient, animal, and simply paying attention to it is all the guidance you need.

ELECTROLYTE LOSS ISN’T A RISK, AND WON’T SLOW YOU DOWN.
If you don’t overhydrate, you simply don’t need to worry about electrolyte imbalances caused by major efforts. “There is no need to replace minerals during exercise, because the loss of minerals has no deleterious effect on the body,” Winger asserts, while noting that this applies to athletes who drink when they are thirsty, and don’t drink constantly. As for taking salt tabs during a race to offset over drinking, Winger says this is also unwise: “During a 26-mile marathon, there is no role during or after the race for oral supplementation of salt.” Winger says the one quick fix for someone who has overhydrated during training or racing is to hit an aid tent or E.R. and get “highly concentrated IV fluids (not normal IV fluids) that will then raise the blood’s concentration.”

WHY DO I FEEL BETTER WHEN I DOWN A RECOVERY DRINK AFTER EXERCISE?
For a somewhat sneaky reason that sports drink makers have taken advantage of, which is that you’re being washed by endorphins when you stop an exercise, and at the same time, you aren’t being taxed by the effort, so you feel better, period. Plus, says Winger, you are thirsty, and quenching that thirst naturally makes us feel better. But lastly, a sports drink nearly always, “…adds carbohydrates. And that’s the preferred fuel for almost every tissue in the body. It may also contain protein, and if that’s the case it supports muscles, too.”

WHAT ABOUT FOOD DURING EXERCISE?
Winger says that if a sports drink has carbs it’s perfectly reasonable to dose with it, especially for workouts lasting longer than an hour, but to be careful that this doesn’t make you over-drink. Gels or an energy bar obviously contain higher concentrations of fuel and make it easier to avoid drinking more than necessary.

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{ 31 comments…read them below or write one }

  • Kim Kircher

    Hmm. Hard to swallow such a turn around (pun intended). I’d heard about this study and hoped it was bogus. Drinking water is one of those maxims I live by. What are they going to tell us next, that crack cocaine enhances performance?

    • steve casimiro

      Actually, it makes sense, and other than calling electrolyte replacements into question, is consistent with what we already know: Drink when you’re thirsty. Calories restore your energy.

  • Rascal

    I have almost died 3 times in the past 2 years from lack of hydration.

    I am not impressed with the study, it’s lack of breadth or depth.

    I work out, am in decent shape, I hydrate a lot, over a gallon a day, and I’m ok when I do that. When I don’t, I do not do well. My case is a little unusual but not that much.

    Water washes toxins out, etc.

    I agree that most bottled drinks are not worth much or are damaging. But water itself is beneficial.

    It is very hard for most people to tell when they are “thirsty”, that is, if their body needs water.

    Boo hiss, for this article and the study. Like Victoria said, I’M NOT CONVINCED.

    • Jay

      The body does not always tell you it needs water by being thirsty. I woke up this morning with a severe headache. My place is almost 90 degrees, I don’t use AC, since I let my body adapt to it. The major heat wave just heat, so am still adapting to it. I am not thirsty at all, but get tired and get headaches, so body has other ways to tell you things.

      • Charmaine

        Like the article says, Jay, when you are thirsty… drink! If you feel thirsty once… drink! If you feel thirsty 10 times… drink! All it says is that there is NO specific gallon amount that anyone can drink that benefits them…. and there IS such a thing as TOO MUCH. There is no such thing as “Sometimes you don’t know when you are thirsty”..!?! You said it yourself… your place was 90 degrees… the signs your body reacted with were guiding you to water… that’s thirst ;)

  • Rascal

    The study was limited to MARATHON RUNNERS.

    That is a tiny fraction of 1 % of the population of people who exercise.

    LAME STUDY AND SHAME ON YOU FOR PRESENTING THIS AS INFORMATION FOR PEOPLE WITHOUT CALLING ATTENTION TO THE LIMITED SCOPE OF THE STUDY. :P LOL

  • Christoph Dollis

    “Drinking water is one of those maxims I live by. What are they going to tell us next, that crack cocaine enhances performance?”

    refraining from overhydrating ≠ crack cocaine

    However, for the record, why do you think cocaine is on virtually every sporting organization’s list of banned substances?

    It enhances performance.

  • TahoeSux

    I’d have to join the chorus of skeptics here. I can buy the “drink when you are thirsty” thing, but any endurance athlete has stories of going too far, or brown pee after a ride/run/paddle/etc. That said, forcing yourself to drink because you think you have to is sort of silly too- unless conditions dictate otherwise (like it’s freaking hot).

    Not to take anything away from marathon runners, but this is adventure journal- and many adventure/endurance athletes go for 5+ hours on a given day. I think this may be of more relevance for people exercising in the 0-3 hour range.

    Anecdotally, I’ve worn a heart rate monitor for years now (15+). I can actually see my cardiac drift to to dehydration on my heart rate monitor. I’ve also run out of water and gotten all gorked out and started making poor decisions due to dehydration. More info is needed on this study. Interesting though.

    • Michael Frank Post author

      This is a reasonable way to think about the study: What do I do as an athlete? What have I experienced? But you can’t take the personal and extrapolate it to the masses. This is a PEER-REVIEWED STUDY. Meaning: The methodology is pure, the sample size is very large, and the conclusions are reasonable. Will this translate to everybody? Nope. But it’s specious to say things like, “marathon runners represent a tiny fraction of the population” when what they do for three hours (a three-hour marathon is VERY fast) or more like 4-6 hours isn’t much different than hiking all day.

      We’re not suggesting for anyone who’s protocol works for them that they should throw it all out the window. But this is the first major study that calls the conventional wisdom into question, and along with the South-African/French study from 2010 (with a sample of over 500 runners) that suggests that mild dehydration actually makes you a more efficient athlete, we certainly think there’s at least enough evidence here to cause reasonable people to scratch their heads and wonder if everything they’ve been taught might not be correct.

      Ah, yes, and the cocaine argument — it probably makes you THINK you’re faster, right? But we’ve also heard it makes you think you can fly…

  • Rascal

    As you say MF, this could be a critical takeaway for many people-critical to their collapse and death:
    “The critical takeaway: We all drink way too much water (and sports drinks), putting ourselves at risk of worse, not better athletic performance.”

    I think it would be hard to come up with a broader, more sweeping, more dangerous generalization.

    Surely you have some level of embarrassment with your statements.
    Drink when you are thirsty? There are so many things wrong with that procedure, time nor keyboards allow response.

    Well… have fun MF.

    • steve casimiro

      Legitimate criticism is encouraged, but personal attacks and general insults will not be tolerated. Please keep your critique specific and on the story or you will be banned from commenting.

  • Rascal

    Steve, I am not sure which of our comments you are referring to but every point I made was valid and accurate.

    The deletion of my earlier comment today exposes your unwillingness to allow valid statements to post here.

  • Graham

    I see a lot of truth in this article. The problem is that it’s misleading and difficult to tell what exactly he is talking about. (it appears to me that this article is written with strictly athletes in mind.)
    I am young, I know my body well, and I am extremely active/athletic. I’ve done triathlons and 24 hour events. I can stay out of the “dehydration zone” merely by counting on the thirst factor. I know my body well enough to know when to and when not to drink. For athletes who are in shape (meaning more than the twice a week jog around the block) and more specifically professional athletes this article makes perfect sense. The tip off is that he is talking about improving performance/speed, not saving you from a visit to the local ER.

    The problem we have is overweight, out of shape and ignorant people who don’t know themselves well enough, dying or ending up in the hospital because they got out for the first time in six months and did something “strenuous.” Either that or they drink solely Gatorade and sports drinks thinking that it “Hydrates you in ways water can’t” (which is pure BS)

    For the overall non-athletic populace the rule of thumb really should be to drink before thirst and supply yourself with electrolytes often. Though, a banana does you more good than a bottle of Gatorade. And believe me, I’ve over-consumed on water before and dealt with some nasty repercussions.

    Drink less water? I don’t think so, It’s a rarity having someone die from over consumption of water.
    There are more deaths related to NOT drinking water than anything. However, knowing your body and its capabilities does more good than just blindly consuming.
    Drink less Gatorade and Coke? Absolutely! It’s pure BS fed to us from multi billion dollar companies trying to turn a dollar.

  • Rob

    Not convinced. I find it hard to believe a full article was written to dispell what conventional wisdom and thousands of other research articles have shown in the past because of ONE recent research article. If I changed the way I did all of my training based off of every article I read, I’d be changing it every day. I would need to see more evidence to support this.

    • Michael Frank Post author

      Rob, you don’t need to be “convinced” of anything. Being skeptical is a better place to be than not.

      However the “conventional wisdom” counter-argument is troubling because it isn’t backed by other study. To say “thousands of research articles” doesn’t provide any proof, any science, any rigor to the idea of drinking when we are NOT thirsty. Why aren’t animals dropping dead all over the place because they only drink when they’re thirsty? Does your dog or cat die because it only drinks when it’s thirsty? It’s like suggesting we should regulate our other bodily functions via a clock; eat when you AREN’T hungry, sleep when you AREN’T sleepy, and so on. Does that seem rational?

      Graham, I agree with your assessment. This piece is focused on athletic people and in large part we do know our bodies better than most. We “read” the messages more clearly, we know what a cramp means, just as we know when to eat, when to back off, when we have the fuel to put in a faster mile, a harder pull.

      However this study was prompted by a worldwide rise in incidence of hyponatremia among athletes, and in particular, among long-distance runners, and a belief that these runners misunderstood the causes of the condition. Most of the runners thought UNDER-hydration caused the illness. It doesn’t. Most thought that the danger of dehydration was far greater than it is; hyponatremia is actually far more common than dehydration and in the past decade has caused 12 deaths in marathons around the world and thousands of runners to become ill. And while, as you say, there are more deaths caused by dehydration than over-hydration in general, this just isn’t true among runners. If you’re that thirsty you stop running. Unfortunately the symptoms of hyponatremia attack slowly, you can run through them, and by the time you’re really unwell at best you have many hours of illness to fight off, and that’s a good-case scenario.

      So you’re on the right track suggesting that listening to our bodies is the correct idea, but the evidence supports educating even novice athletes to do so, because they’re making themselves sick and there’s no good reason for it.

  • Greg

    @ Michael Frank

    What I take issue with is not drinking to thirst, but rather your very poor scientific reporting.

    Your very first assertion that the cited paper recently published by Dr. Winger (http://www.ncbi.nlm.nih.gov/pubmed/20876587) concludes that drinking to thirst is the best method of hydration is incorrect. The paper does not even attempt to identify the “best” method of hydration but rather “To determine the beliefs about fluid replacement held by runners and whether these beliefs are reflected in hydration behaviors.” Strike one.

    You immediately follow that up with “The critical take away: we all drink too much water.” Actually that is completely contrary to what the study did find: “the majority of runners (55.7% [of respondents]) answered that they drink only when thirsty.” Which, according to USA Track and Field, the International Marathon Medical Directors Association, the authors of the paper, and your own article, all recommend as the CORRECT (and scientifically supported) method of hydration. Strike two.

    Next you report that “if you drink when you’re thirsty rather than before, you’ll maintain perfectly adequate hydration. In fact, more experienced, and often faster runners in the study did just that” Again, you appear to not have read the actually study which reports that the fastest (50 min. average 10k compared to 52 min and 60 min), and most experienced (12.9 average years running experiences compared to 8.2 and 10.1 years) runners drink to a schedule, rather than to thirst or “as much as possible”. Further, those two distinctions (10k personal best and years of running experience) were not statistically significant. The only distinction that was statistically significant was the only one you failed to mention: age. Strike three.

    Finally, I would like to point out that the cited study was conducted on 197 self-reporting runners that averaged less then 1 completed marathon, and just over 1 (~1.2) half-marathons. This is not a group of runners that I would consider either elite or well experienced. In the discussion the authors themselves point out “a low response rate and bias of self-reporting.”

    In conclusion I believe that your reporting of the this study was very poor. I felt that the details and findings of the paper were not accurately represented in this article, and in some cases completely misrepresented or wrong. While drinking to thirst is the scientifically supported and recommended method of hydration, that is not what this study demonstrated or was intended to show.

  • Jason

    I have been overhydrated, what happens is you flush all the sodium out of your body. It can also cause your kidneys to fail, and seizers. Now you may dismiss what I have said, but I’ve been in the hospital twice for IV fluids due to overhydration. So I can back this article without question.

  • Scott

    The “8 glasses a day” maxim is a myth, brought on by an omission in an early USDA nutrition report. The original statement was that the body required roughly the equivalent of 8 glasses per day but that much of it was taken in with food. The last part was subsequently omitted and we’ve hysterical foodies and a 6 billion dollar a year bottle water lobby in DC as the result.

    http://www.snopes.com/medical/myths/8glasses.asp

    In my own experience, 8 glasses of water a day while I’m sitting in an office would have my back teeth floating. 8 glasses a day while hiking in the desert would have me in real trouble from dehydration.

  • Talia

    What confuses me about this article is that it completely neglects to mention that when you’re doing 70, 80, 90, 100 mile weeks, you’re pretty much always thirsty.

  • tim

    This all came about from soda, not OH GET YOUR DAILY AMOUNT O WATER. When you drink soda it so sugar laden you need a lot of liquids to deal with the excess sugars. So if all you drink is soda you can easily go thru a 2liter because your body is constantly thirsty. I remember my science teacher explaining it to us in middle school WAY back when. It was to get kids to intake water to be able to properly use and flush the excess sugars and keep from becoming fat and lazy.

  • Ernie Boxall

    I’ve never done research, and after forty years in the fitness industry have seen scientific “truths” of one decade demolished in the next. So just on a personal note I have to say that I find it almost impossible to drink plain water and always have done yet I always based any sporting success I had on endurance.
    In soccer and rugby football it was always my ability to run “forever” rather than speed that got me by.
    So, while I’m always reminding my clients to drink water when they need to, I drink other fluids.

  • gaspar

    our body has the ability to compensate with overhydration during exercise..perspiration, and besides it was never mentioned in physiology books that water dilutes the blood.

  • Chad

    I think it is funny that we have gotten so far away from listening to our body’s to tell us what they need, that an article reminding us of the amazing tool our body is can cause such an uproar. It makes me wonder how the ancients survived with out the conventional wisdom of today. I have found that if i just slow down and listen to my body I’m rarely deceived. In fact it makes me even more grateful for the great gift my creator has given me.

  • Hope Peek

    I also heard something like this on the TODAY show this week and I really hate it when journalist try to spin the story a certain way referencing 1 particular study. They still tell you to drink water when your thirsty; and you are always thirsty when working out. I can remember at my daughter’s Soccer camps and the Coach went as far as to say that, if your pee is at all yellow, that you are not drinking enough water, and this is a multi-time title winner for the NCAA Soccer Championships for both Men and Women, and he referenced studies indicating just what he said. On a personal note, I have very low blood pressure, and sometimes feel faint when standing too fast, they call it a vasal vagus syncope, and the only way to prevent it is to never miss breakfast and to hydrate as much as possible and limit caffeine. So as an avid swimmer, I can’t get enough water. It’s healthy, no calories, and I also love the Soda Stream machine for carbonated water which does a better job quenching my thirst.

  • mark

    I read your study, and raise you another one that says that sodium drinks are good to consume! Studies are a dim a dozen and you always need to read the fine print to see who they are referencing. Dr. Winger cites a couple of very small, < 10 people studies as a reason why drinking water with sodium does not reduce the chances of getting hyponatremia.

    From the below study:
    "We, therefore, recommend consumption of a sodium-containing beverage to compensate for large sweat losses incurred during exercise."

    Sodium-free fluid ingestion decreases plasma sodium during exercise in the heat.
    Vrijens DM, Rehrer NJ.

    http://www.ncbi.nlm.nih.gov/pubmed/10368348

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