The Hydration Nation: Hyper-Hydration vs. Dehydration

20140501“Are you drinking water?” “Drink water!” “Hydrate!” “If you’re thirsty it is too late, you are already dehydrated.”  This craze of hydrate, hydrate, hydrate has gone overboard and could be causing more harm than good. Who is more at risk for serious medical complications, the hyper-hydrated or dehydrated. For performance, is it best to be overly hydrated, dehydrated or euhydrated? What follows might surprise you.

Doctor Tim Noakes, MD a long-time researcher of water balance and author of “Waterlogged:  The Serious Problem of Overhydration in Endurance Sports”, says we have been misled to believe that we need to drink to stay ‘ahead of thirst’.  How have we been misled? First, we can thank the hydration industry for funding dubious science. Second, the fear mongering media jumps on board and purports untrustworthy science. And finally, we confuse the issue by generically using the term “dehydration” to describe the symptoms of heat exhaustion, heat cramps, or heat syncope.

Before I go further, let me clarify that I am NOT saying dehydration is a good thing. It is well-documented that a loss of just 2% of body water yields performance loss. When we have dehydration of 5% we enter a level for more serious health risk. However, that does not mean we should overhydrate. Our obsession with hydration puts us at risk for water intoxication, which has serious consequences. A 2% increase in total body water leads to generalized edema that can impair physical and mental performance (1).

For athletes, overhydration leads to performance loss and puts athletes at risk for exercise-associated hyponatremia (EAH) or exercise-associated hyponatremia encephalopathy (EAHE) –a potentially fatal condition. Oftentimes when an athlete collapses our first order to triage is to rehydrate. However, according to Noakes, the two most likely exercise-related causes of collapse during exercise are heat stroke and EAHE (2). Adding more fluid could exacerbate the issue. Intravenous fluid therapy should only be given if the athlete has elevated blood sodium concentration levels (hypernatremia). Take a look at the table below and note that the signs and symptoms of EAH, EAHE, and heat-illness are similar.

Signs and Symptoms of EAH, EAHE, Dehydration, and Heat Exhaustion

EAH EAHE Dehydration Heat Exhaustion
Nausea Headache Dry mouth / Thirst Confusion
Vomiting Altered level of consciousness Weakness Fainting
Unexplained fatigue Coma  Dizziness Dizziness
Impaired exercise performance Convulsion/Seizure Confusion Headache
Inability to sweat Profuse sweating

Ironically, I was working at a hydration station during the Illinois Marathon last weekend.. I witnessed several runners being carted away by emergency medical crews and all had an IV hooked up. Now, I was not the attending EMT. I did not perform the initial assessment, but all of these individuals required IV? Assuming the athletes hydrate before the run and have access to water all along the course, did all of these athletes truly need an IV? Where they all dehydrated, or were they suffering from other conditions? A study published in the British Medical Journal(2007) examined twenty-six U.S. marathons over this thirty-year period. The authors found four deaths from water intoxication and hyponatremia and zero from dehydration.

20140426_124445Two old and likely dated position stands have recommendations that could lead to overhydration. American College of Sports Medicine (ACSM, 2007), recommends drinking 20 to 40 fl oz per hour before and during endurance events (3). The NATA position statement of 2000 says athletes should consume approximately 17 to 20 fl oz 2 to 3 hours before exercise and 7 to 10 fl oz 10 to 20 minutes before exercise for a total of 24-30 fl oz. Unfortunately, this may be excessive. As fluid intake exceeds 800 ml (27 fl oz) our risk for EAH increases, and for fluid intake over 1000 ml (34 fl oz), the risk goes up significantly. Two major organizations recommend fluid intakes that put athletes at risk. Maybe it is time we reexamine these standards?

Then there is the issue of hydration on performance.  Much like adding water to gas, we are diluting our fuel. Adding water to blood dilutes sodium, potassium, and other needed elements required for performance. Studies show that when athletes exercise at euhydration levels performance is optimal. Performance gradually declines as we move further from euhydration to hyper-hydrated or dehydrated.

A study released by the NSCA demonstrated that pre-exercise consumption of an energy drink did not improve cycling performance. In addition, the data indicates that energy drinks induced greater inflammatory-related responses than caffeine and carbohydrate supplement or a Placebo (sparkling water) (5). Even more, consumption of energy drink elicited mild  hypoglycemia during cycling (5). The authors conclude that coaches and sports medicine personnel should be cognizant of consumption timing before competition and remember that energy drinks contain a significant glucose load.

The final advice from Tim Noakes is that athletes “should drink at one’s own discretion and listen to their internal thirst mechanism”. Dr. Noakes states we should aim for ingestion rates that never exceed 800 ml/hr (27 ounces)(2). If you maximize performance stay balanced – not too much, and not too little. Instead of drinking to prevent thirst, listen to your thirst mechanism and drink at thirst. Remember this should not be taken as the Gold Standard. Everyone is different. Experiment with various hydration strategies to learn what works best for you. Try different sports drinks in varying amounts, and hydrate at different times during your workout to discover the optimal mix.

That is all for now. Whew –  I’m thirsty, time for some water.



1. Cohen, D. The Truth About Sports Drinks. BMJ 2012;345:e6096

2. Noakes, T. Waterlogged: The Serious Problem of Overhydration in Endurance Athletes. Human Kinetics. Champaign, IL. 2012.

3. ACSM. ACSM Position Stand; Exercise and Fluid Replacement. Med Sci in Sport and Ex.2007; 39(2)

4. Casa,DJ, et. al. National Athletic Trainers’ Association Position Statement:  Fluid Replacement for Athletes. NATA Journal of Athletic Training 2000;35(2):212–224

5. Phillips, MD, Rola, KS, Christensen, KV, Ross, JW, and Mitchell, JB. Preexercise energy drink consumption does not improve endurance cycling performance but increases lactate, monocyte, and interleukin-6 response. J Strength Cond Res 28(5): 1443–1453, 2014.


12 thoughts on “The Hydration Nation: Hyper-Hydration vs. Dehydration


    Thank you for this article, I have wondered if I am drinking too much. I consume about 20 oz/hr and sweat profusely during exercise.

  2. Dyl

    Quick question regarding your claim:

    “It is well-documented that a loss of just 2% of body water yields performance loss.”

    2nd sentence, 3rd paragraph, you state this – right after you quote Dr. Tim Noakes “Waterlogged” book. You realize that he [Dr. Tim Noakes] debunks this myth in this book? And shows multiple studies that the best performances were those of individuals whose total boy water loss was that of ~2% or greater.

    1. Joshua Stone Post author

      Thank you for the comment and yes I do realize this. I actually had that line in the article, however, there is also a slew of evidence that goes the other way. Thus, I left it out.

      1. Dyl


        But is it not merely how the evidence is interpolated? As in, the studies that have shown performance decline were not actually performance based, rather they based the claims solely off of core temperatures of the subjects that participated in the study.

        Another thing Dr. Tim Noakes explains in the book.

        1. Dyl

          Just to clarify the above,

          Dr. Tim Noakes goes into detail regarding this, that the evidence isn’t what it actually claims to be:

          See the following for more details:

          Noakes TD, Adams BA, Myburgh KH, Greef C, Lotz T, Nathan M. 1988. The danger of inadequate water intake during prolonged exercise. Eur J Appl Physiol 57:210–219.

          Sawka MN, Noakes TD. 2007. Does dehydration impair exercise performance? Med Sci Sports Exerc 39:1209–1217.

          Goulet EDB. 2013. Effect of exercise-induced dehydration on endurance performance: evaluating the impact of exercise protocols on outcomes using a meta-analytic procedure. Br J Sports Med 47:679–686.

  3. Tiger Tracks

    Hooray! I’ve been ‘gently scolding’ some of my clients who have bought lock, stock, and barrel into the hydration myth. I can’t begin to count how many of them arrive with fully-loaded Nalgenes or how many disposable bottles of water are left behind in my therapeutic massage studio. I usually use their contents to water the plants! … There was a reason why you were born with a thirst mechanism, so maybe you should respect it. Hyponatremia and edema aside, waterlogging yourself can lead to a host of other things, including an unnecessary buildup of mucous and phlegm, for those of you who are prone to overproduction of the goopy stuff in the first place. That leads to other problems, including sluggish liver functions, a swollen tongue and gums, and eustachian tube dysfunction. … Thank you so much for yet another challenge, along with your recent RICE article, to some widely-accepted ideas about health maintenance.

  4. Pingback: Are you drinking enough or too much | Performance Sports Therapy

  5. Phil

    This is certainly is an area of interest that needs further exploration. Josh I am wondering if you could also present more on the physiology of the thirst mechanism?

    Basic human physiology is built on negative feedback. Which is how the thermoregulatory and thirst mechanism work in my understanding. That process would explain (partially) why you might be low on fluids because thirst is not activated until fluids are below threshold. Granted the body attempts every effort to then maintain fluid balance.

    Same can be said with the thermoregulatory system. If thebody temperature rises then we turn on mechanism to cool us down. Ie sweating. This leads me too the connection between fluid loss and heat illness. Just like the radiator on a car. So I am not a fan of this trend of not linking fluid loss to heat illness Granted treatments are different but I believe they are obviously link.

    Finally the comment about winning the marathon does not prove that the athlete that won did or did not suffer from a loss of performance due to fluid loss or dehydration. All it means is that his performance was better than the competition. People in race mode self regulate effort according to physiological performance so suggesting that just because you win you did not suffer from some levels of dehydration is just miss leading. That is why laboratory test make sense. You can’t self adjust you either perform as the protocol dictates or you stop.

    Thanks for the stimulating conversation and I agree that we need a moderate view towards hydration practices


    1. Joshua Stone Post author

      Thanks, Phil.

      I do not think this is a trend that heat illness and hydration are not correlated. It’s built on the evidence at hand. Thus far, the link does not exist.

      I can agree on your marathon timing and hydration levels comment, which is why I wrote this article. Performance appears to be self, not hydration regulated.

  6. Sandra Fowkes Godek

    Overall, this article is right on. I have shared many times and tagged others who have also shared on FB. The most important point I’d like to make is the 2% cutoff is pretty irrelevant because it depends on the hydration state of the person at the start of the exercise bout. Most studies that indicate performance decrements actually pre-dehydrate the subjects so that they are significantly hypo hydrated prior to the study trial. If anyone is interested in the best, most recent international consensus statement can be found here:

    Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015
    Hew-Butler, Tamara DPM, PhD*; Rosner, Mitchell H. MD†; Fowkes-Godek, Sandra PhD, ATC‡; Dugas, Jonathan P. PhD§; Hoffman, Martin D. MD¶; Lewis, Douglas P. MD‖; Maughan, Ronald J. PhD**; Miller, Kevin C. PhD, ATC††; Montain, Scott J. PhD‡‡; Rehrer, Nancy J. PhD§§; Roberts, William O. MD, MSc¶¶; Rogers, Ian R. MBBS‖‖; Siegel, Arthur J. MD***; Stuempfle, Kristin J. PhD†††; Winger, James M. MD‡‡‡; Verbalis, Joseph G. MD§§§


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