By Dr. Mercola
In an effort to prevent dehydration, it’s common for many endurance athletes to guzzle down large amounts of fluids before, during and after competing.
The American College of Sports Medicine (ACSM) even encourages this approach, stating that “the goal of drinking during exercise is to prevent excessive (>2% body weight loss from water deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance.”i
But is this really the right thing, or the healthiest thing, to do?
Exercise scientist (and experienced endurance athlete) Dr. Tim Noakes doesn’t believe so -- in fact, he points out at least a dozen deaths that have occurred in endurance events due to drinking too much fluid.
Intrigued as to how this problem came about, Dr. Noakes studied the hydration fad over the last few decades, then wrote a book about it, “Waterlogged: The Serious Problem of Overhydration in Endurance Sports.”
The topic is particularly dear to him because 30 years ago he personally advised people to drink as much as they could―only to find out later that this advice could be deadly.
The Problem With Drinking Too Much During Exercise
According to a survey by Loyal University researchers, over 36 percent of runners drink according to a preset schedule or to maintain a certain body weight.ii Another 9 percent drink as much as they can during races. These runners are choosing to ignore their body’s thirst mechanism and instead use other methods to dictate their water consumption, which they believe, mistakenly, to be superior.
Many buy into this belief, and health agencies and sports drinks advertisers have been spouting the misinformation for years. But as the Loyola researchers noted:iii
“These beliefs are frequently based on misconceptions about basic exercise physiology.”
Overhydrating will actually worsen athletic performance, not improve it. As you begin to consume too much water, your cells will start to swell, leading to such symptoms as gastrointestinal upset, dizziness, soreness and others. In severe cases, the sodium levels in your blood may drop to dangerously low levels, causing hyponatremia -- a condition in which your cells swell with too much water. While most of your body's cells can handle this swelling, your brain cells cannot, and most of the symptoms are caused by brain swelling.
This condition is most common among athletes, although anyone can be affected by drinking excessive amounts of water. Dr. Noakes explained:iv
“The brain swells, and because it is in a rigid skull, it cannot swell very much. The more it swells, the more pressure, and that eventually squeezes the arteries supplying blood to the brain. Ultimately, there is less oxygen getting to the brain, and certain parts become damaged. Once it affects your breathing centers, then you’re in real trouble, because it stops breathing, and that is essentially irreversible.”
Your Body is Designed to Tell You When to Drink
According to Dr. Noakes, the first drinking guidelines put out by The American College of Sports Medicine said that runners should “drink regularly during exercise,” which is fair advice. But then an individual working for the U.S. military published a paper saying that U.S. soldiers should drink 64 ounces of water per hour in order to improve performance.
Though the paper was not based on concrete evidence, it was widely embraced by the military, and then filtered through to the American College of Sports Medicine’s guidelines for runners. Today ACSM still recommends drinking “ahead of thirst,” a move that Dr. Noakes says “impairs exercise performance.” He uses the example of African hunters who were able to chase down an antelope for four to six hours in mid-day heat, without a source of fluids until after the hunt ended (when they would drink the animal’s blood and intestinal water). He continues:v
“Dehydration is not a disease, and it only has one symptom, and that is thirst. If you start to exercise, and you don’t drink, after a period of time, you will become thirsty—that’s your body’s way of telling you to drink.
The idea that you should drink ahead of thirst is absolutely nonsensical... why should humans be different from every other creature on earth to be told when and how to drink? The reality is you don’t need to be told when and how much to drink.
We have a 300 million year developed system that tells you with exquisite accuracy how much you need to drink and when you need to drink. It’s called thirst. If you rely on thirst you won’t ever become dehydrated, and you won’t also ever become overhydrated.”
Are Sports Drinks Really Necessary?
Aside from the now disproven dogma that you need to chug lots of water during exercise, it’s also commonly said that you need to replace your electrolyte balance … and sports drinks are positioned as the ideal way to do so. But according to Dr. James Winger, author of the Loyola study:vi
“There is no need to replace minerals during exercise, because the loss of minerals has no deleterious effect on the body.”
The fact of the matter is, sports drinks represent a nearly $4-billion market in the United States.vii And because of their glitzy marketing campaigns, which often feature celebrity athletes, many people are under the impression that these drinks are healthy and essential during or after a workout, offering such benefits as improved athletic performance, increased energy and superior hydration during exercise.
The leading brands of sports drinks on the market typically contain as much as two-thirds the sugar of sodas and more sodium. They also often contain high-fructose corn syrup (HFCS).
Fructose is known to be highly toxic when consumed at levels beyond which glycogen stores are replenished. The excess either converts to triglycerides in the liver, which in turn raises your risk of heart disease and does nothing to satisfy the immediate glucose needs of your cells, or accumulates in the blood where it reacts with proteins through the Malliard reaction (glycation), essentially “gumming up the works” with destructive glycation byproducts that cause accelerated aging and diabetes complications, to name but a few of their adverse effects.
And if that's not bad enough, crystalline fructose may be contaminated with arsenic, lead, chloride and heavy metals.
Many sports drinks also contain artificial sweeteners (they can lead to impaired kidney function, depression, headaches, infertility, brain tumors, and a long list of other serious health problems), artificial flavors and food coloring, which has been connected to a variety of health problems, including allergic reactions, hyperactivity, decreased IQ in children, and numerous forms of cancer.
Not to mention, sports drinks are up to 30 times more erosive to your teeth than water. And brushing your teeth won’t help because the citric acid in the sports drink will soften your tooth enamel so much it could be damaged by brushing.
It’s just not worth it, especially considering only a very small portion of exercisers work out hard enough that a sports drink might be necessary. They basically “work” because they contain high amounts of sodium (processed salt), which is meant to replenish the electrolytes you lose while sweating. But as Dr. Winger said, this isn’t even necessary during a marathon, let alone during most regular workouts:viii
““During a 26-mile marathon, there is no role during or after the race for oral supplementation of salt.”
And even then, if you did feel a beverage other than water was necessary, coconut water is a far better choice than virtually any commercial sports drink on the market.
So How Much Water is Healthy?
Even if you’re not an endurance athlete who is chugging 64 ounces of water an hour, you may still be stressing yourself unnecessarily regarding your water consumption. Scientific evidence to support the widely touted recommendation to drink eight glasses of water a day is also lacking, and has even been called “thoroughly debunked nonsense.”
Drinking eight 8-ounce glasses of pure water a day may not be likely to cause you harm; it’s just that the evidence is lacking on whether that is the magic number for everyone, and most likely it appears that it is not. The reality is that many people are dehydrated and would benefit from drinking more water each day, and from making water their primary source of fluids.
Your body will tell you when it's time to replenish your water supply, because once your body has lost between one to two percent of its total water, your thirst mechanism lets you know that it's time to drink some water!
The color of your urine will also help you determine whether or not you might need to drink more. As long as you are not taking riboflavin (vitamin B2, also found in most multi-vitamins), which fluoresces and turns your urine bright yellow, then your urine should be a very light-colored yellow. If it is a deep, dark yellow then you are likely not drinking enough water. If your urine is scant or if you haven't urinated in many hours, that too is an indication that you're not drinking enough. (Based on the results from a few different studies, a healthy person urinates on average about seven or eight times a day.)
But since your body is capable of telling you its needs, you needn’t worry about measuring your water intake or counting your glasses. Simply using thirst as a guide to how much water you need to drink is a simple way to help ensure your individual needs are met, day-by-day.
Of course, if it's hot, exceptionally dry outside, or if you are engaged in exercise or other vigorous activity, you will require more water than normal. But again, if you drink as soon as you feel thirsty, you should be able to remain properly hydrated even in these cases.