Food Freedom Friday Edition 296 - Overhydration

Water is legitimately the answer to all of your problems. 

Want to boost your metabolism? Drink more water. 

Want glowing, clear skin? Drink more water.

Want to meet your fitness goals? Drink more water.

You have probably been told over and over that staying hydrated is the best thing you can possibly do for your health—but can there be too much of a good thing? The golden rule is eight glasses per day, which already seems like a stretch to some but can be a walk in the park for others. Everyone’s body is completely different, which means the recommended water intake can vary depending on the person.

Everything has its limits, and, as healthy as water is, it is certainly not excluded from that narrative. Overhydrating yourself is a serious scenario that can lead to dangerous health conditions known as hyponatremia or water toxicity. It can happen to anyone who overdoses on the amount of water they are consuming.

The effects of excessive water consumption are not just due to the total amount consumed. Water toxicity can also be a result of drinking too much water too quickly. People may just experience mild effects of "water overdose" at first, with more dangerous effects to follow if consumption continues.

The Consequences of Too Much Water

Your body works to maintain normal function despite the regular variations in fluid levels that you experience throughout the day. The first way your body manages water overload is by simply removing the excess fluid through urine. If you drink too much fluid, you will initially balance out your body's fluid by urinating more. For the most part, your body can keep up if you repeatedly drink more water than you need.

However, the rapid consumption of large amounts of water can overwhelm the body’s natural ability to maintain normal fluid balance. This causes excess fluid to enter the brain, resulting in brain swelling. Symptoms of brain swelling may include:

·       Confusion

·       Headache

·       Drowsiness, lethargy

·       Dizziness (vertigo) 

·       Severe symptoms including sudden unexpected loss of consciousness, seizures, or stroke.

When the body takes in extreme amounts of fluid, the excess water enters brain cells through osmosis. This causes brain tissue compression and lack of normal function. Brain cells may experience a disruption to their normal calcium and sodium concentration. This results in the symptoms that may include light-headedness, dizziness, or confusion.

Hyponatremia, having an abnormally low amount of sodium in the bloodstream, can contribute to the symptoms of nausea, vomiting, or muscle cramps. The condition can also cause brain cell death from physical compression and electrolyte/water imbalances. Hyponatremia can be very difficult to manage medically because it progresses so rapidly and the damage is so severe.

8 Glasses A Day

The confusion started in the 1940s. The US National Academy of Sciences advised drinking 84 ounces of water per day. This was not an evidence-based recommendation and had no science behind it.

In the 1960s, 84 ounces became 64 ounces. Irwin Stillman, a physician, recommended drinking eight glasses of water eight times per day. This “8x8” rule also was not evidence-based, but it was memorable.

Today, many people take this to be fact with many believing that drinking more water is healthier, period. The concern is always oriented around preventing dehydration.

There is very little mention of overhydration. This is an unfortunate oversight for the exercise community, because overhydration has proven to be more dangerous than dehydration.

It’s worth mentioning that most biological systems requiring inputs have U- shaped curves. Problems occur with both too much or too little of a given substance or exposure. More is not always better!

Hydration Myths

It has been shown that most websites, even scientific ones, give poor hydration advice. Most websites dish out lousy hydration advice.

Some of the most widespread hydration myths include:

Overhydration Is Not Dangerous

Most sources barely cover the dangers of overhydration. They fail to mention that excessive fluid consumption is the main cause of exercise-associated hyponatremia.

Hyponatremia occurs when fluid intake exceeds fluid losses through sweat, urine, and respiration. When too much fluid enters the bloodstream, it dilutes blood sodium levels – this is hyponatremia.

Athletes are especially prone to hyponatremia. They lose both water and sodium through sweat, but tend to only replace water and often too aggressively thanks to the ‘drink more water’ advice.

Antidiuretic hormone (ADH) is also suppressed during exercise, decreasing urinary volume. This results in athletes being unable to excrete excess fluids which creates further problems when overhydrating.

Drinking large amounts of water without electrolytes and then training hard could be very troublesome. On top of diluting electrolytes, normal kidney function will be slow to remove the excess water.

Furthermore, hard exercise:

·       Breaks down glycogen, which releases water into circulation.

·       May increase absorption of fluids through the gut.

·       May decrease the mobilization of sodium from bone and soft tissue.

When you combine these risk factors, the risk of hyponatremia is amplified further.

Drinking To Thirst Is Insufficient

Very few experts (especially online) recommend drinking to thirst to support both day-to-day life and exercise. Drinking to thirst is said to be insufficient to prevent dehydration. Guidelines urge drinking to prevent mass loss, especially in exercise or heat.

Weight loss, however, is not an accurate guide to dehydration. You can lose body weight when sweating excessively still maintain adequate body water.

This can most likely happen when water from muscle and liver glycogen (stored glucose) becomes liberated during exercise or excessive sweating and enters circulation to maintain blood volume. It appears humans have backup water stores.

Thirst is an excellent guide to hydration needs. It is triggered by a tightly-calibrated system of osmoreceptors that monitor fluid and electrolyte levels in the blood. When blood volume gets too low, or when electrolyte concentration gets too high, you will get thirsty.

Multiple studies also show that drinking to thirst is sufficient to maintain fluid balance even during hard exercise. Drinking beyond your thirst puts you at risk for overhydrating and the consequences that ensue.

Dehydration Causes Heatstroke

A common argument for drinking more water is that dehydration may impede your ability to cool yourself with sweat and your risk of heatstroke will go up.

This myth is all pervasive. The majority of hydration-related websites warn that dehydration causes heat illness.

Interestingly, the evidence contradicts this assumption:

·       Heatstroke during exercise occurs with or without dehydration. The notable risk factor is exercise intensity, not hydration status.

·       Drinking more fluid fails cool you off – the physiological process is different and more complex than this simple formula.

·       Research has even shown that dehydrated athletes may stop exercising at lower core body temperatures compared to hydrated controls.

·       Dehydration has been found to not impair performance in the heat.

The large majority cases of heat illness happen in very young or very old people due to the slower sweat mechanisms in these groups. Hydration status plays no role.

Overhydration Symptoms

The symptoms of overhydration are in essence the symptoms of hyponatremia. Hyponatremia symptoms can be categorized in one of two ways:

1.     Mild to moderate hyponatremia symptoms that can be handled simply.

2.     Severe hyponatremia symptoms that likely require medical attention.

Certain symptoms may overlap in these categories and thus every case should be treated individually.

Mild To Moderate Hyponatremia Symptoms

The early symptoms of hyponatremia include dizziness, fatigue, mild nausea, and bloating. As the condition worsens, the hyponatremic person may also experience:

·       Headache

·       Confusion

·       Irritability

·       Light sensitivity

·       Vomiting

·       Drowsiness

·       Difficulty breathing

·       Altered cognition

Tim Noakes, a sports doctor who has studied overhydration in athletes has seen many of these symptoms in the distance athletes he’s treated. He’s seen more severe symptoms too.

Severe Hyponatremia Symptoms

Noakes explains that the usual hyponatremic person becomes confused and very typically loses consciousness or alternatively loses consciousness and suffers an epileptic seizure.

Severe hyponatremia symptoms include:

·       Seizures

·       Coma

·       Abnormal posturing (a sign of brain damage)

·       Dilated pupils

In these cases, urgent treatment with IV hypertonic saline fluids (saltwater) is required or the person may die.

Treating Overhydration & Hyponatremia

There are three main treatments for overhydration:

1.     Restrict sodium-free fluids

2.     Drink salty water

3.     Intravenous (IV) saline

Use treatments the first two options when dealing with mild to moderate hyponatremia. The overhydrated person should stop drinking water and start drinking a hypertonic solution containing about 3% sodium chloride (salt). That’s the equivalent of putting 32 bouillon cubes in a liter of water.

There is some controversy over oral salt water as opposed to IV saline for treating hyponatremia. A few studies suggest it works adequately with oral saline being possibly just as effective as IV saline for reversing hyponatremia.

For severe cases of hyponatremia, IV saline is the best option. The patient may be unable to hold fluids down or even be unconscious. This treatment should obviously be administered by a qualified medical professional.

Preventing Overhydration

Most people are constantly concerned about dehydration, but overhydration is the more pressing problem. There are a few easily implementable, practical takeaways for preventing overhydration and the resulting hyponatremia:

·       Drink to thirst. Drinking to thirst prevents both overhydration and dehydration. Your body knows when to stop consuming fluids. You need only listen.

·       Reduce the availability of regular water. It is acceptable to become slightly dehydrated during exercise. Constant hydration increases the risk of overhydration.

·       Factor in body weight. If you are gaining weight during training sessions, it probably means you are drinking too much water. Losing 1-2% of mass after exercise is normal.

·       Add salt to your water. Drinking a salt water solution can prevent and reverse hyponatremia.

There is no universally accepted, health-based recommendation for a daily amount of water people need. This amount will differ daily depending on what you eat, where you live, and what are doing, like working in an air-conditioned office versus going for a summer run.

The Bottom Line

Water consumption is an important part of healthy body function, athletic performance and balance. Drinking water is generally good for you. That being said, drinking an excessive amount of water can have health consequences ranging from mild to serious. The key to a healthy lifestyle is understanding that more is not always better! Although it is possible to drink too much water, when it comes to proper hydration, the human body has a highly sensitive, built-in gauge: Drink to quench thirst, but not beyond.