You probably can’t count the number of times you’ve been told to drink lots of water, stay hydrated, drink before you get thirsty, etc. — especially when you’re exercising. And at face value — and further — this is solid advice. Your body needs water to perform its basic functions, the sweat you lose when you exercise needs to be replaced — you get the picture.

But what about the opposite end of the spectrum? Is it possible to drink too much water in a day? Is that a thing?

Well, the short answer is actually yes. If you drink too much water, you can cause sodium (salt) levels in your body to be diluted to a dangerously low level, disrupting your electrolyte balance– and that can have serious effects on your health if not corrected.

But how do you get to that point? Why? How much water is too much?

How much water do you actually need?

Before you dive into the details — and they get a bit heavy — take a minute and review the relationship between water and your body. Firstly, alongside food and oxygen, water is important to survival. With as much as 60% of your total body weight coming from water, it’s actually the principal element making up you.

Water helps you regulate your body temperature (think sweating), helps to transport nutrients through your bloodstream, flushes waste out through urine, and acts as “padding” for all of your organs — just to name a few functions. Water has its fingers into literally every part of your body, from the cell-level up — it’s so important that if you don’t drink enough, the effects can be lethal in just days.

When you don’t drink enough water, you get dehydrated. Even mild dehydration can make you feel tired, reduce your cognitive awareness, and decrease your exercise performance. And as already mentioned, severe dehydration can kill you.

Currently, the National Academies of Sciences, Engineering, and Medicine offer some fairly concrete recommendations for regular individuals:

• Men should drink approximately 3.7 liters (125 ounces) of fluids each day; and

• Women should drink about 2.7 liters (91 ounces) per day.

But keep in mind, these recommendations are for ordinary individuals going about their regular day to day — not athletes or exercising people. So that being said, you may need to increase your intake of water when you are exercising intensely and in hot or humid weather. Pregnant or breastfeeding women may also need to increase water intake, as hydration needs differ.

But overhydration?

So that’s getting enough water, and too little, but what about drinking too much? Again — drinking too much water is possible.

In 2003, a 64 year-old woman was found dead in her home. The night before she passed, she drank water in tremendous quantities — an estimated 30-40 glasses, interspersed with repeated vomiting. She became increasingly disoriented and distressed, yelling about how she had not drank enough water. After declining to obtain medical attention, she went to bed and died at some point during her sleep.

Given that the woman had no relevant previous medical history, a postmortem exam was performed 6 hours later. Blood toxicology ruled out many causes of death, and it was ultimately determined that she had died of “hyponatremia as a result of acute water intoxication.”

Another study was performed on ultradistance triathletes. Included in this study were 605 of 660 athletes who had entered into a New Zealand Ironman triathlon. Prior to the race, they were weighed and had blood drawn for a measurement of their blood plasma sodium concentrations. The lab results of just 330 of the race finishers was available following the conclusion of the study.

Of these 330, 58 (18%) were hyponatremic (low sodium levels); of these, just 18 received medical attention; 11 of these 18 were severely hyponatremic; and 7 of these 11 have symptoms of severe hyponatremia. The study concluded that while hyponatremia is a common finding in distance athletes, it’s usually non-symptomatic — and in the case of 73% of the severely hyponatremic athletes studied, fluid overload was the cause.

There are many other cases that can be reviewed — but the answer is clear and concrete: you can drink too much water.

How does this happen?

Wait, so how does that work? To understand that, you need to know how your body handles water, salt, and waste materials.

Normally your kidneys act as “filters” of waste material. Your blood is carried to your kidneys by way of the renal arteries. As it passes through the kidneys, excess fluid and waste material is removed by little units called nephrons. Some of these materials being filtered include things like sodium, among others. Whatever your body still needs is reabsorbed into the bloodstream — the rest is sent to your ureters to be removed in your urine.

But, when you drink fluids in excess, you can overwhelm your kidneys’ ability to excrete it all. This leads to your body retaining fluid and causes something called hyponatremia — don’t worry about that term right now — it’ll be discussed shortly. If you have pre-existing kidney problems, your kidneys are at an even greater risk for this condition, and you may be more susceptible.

Water intoxication

When you overwhelm your body’s ability to excrete the water and waste products you take in, you develop water intoxication — the same condition that killed the 64-year-old woman mentioned earlier. Water intoxication causes disturbances in the electrolyte balance of your body, causing a life-threatening condition known as hyponatremia. With a rapid decrease the sodium levels in your blood, relative to the amount of water, symptoms can quickly develop:

• Early symptoms can include confusion, disorientation, nausea and vomiting, as well as changes in your mental state, or symptoms of psychosis.

• Later symptoms can develop, if left untreated, into seizures, coma, and eventually death.

So what is ‘hyponatremia?’

Now that it’s been mentioned several times, what’s hyponatremia? Essentially, it’s a low salt concentration in your body and is the most frequent dyselectrolytemia, or abnormal electrolyte disorder. It’s classified quantifiably as a decrease in serum sodium concentration of below 136 mmol/liter of blood.

But it’s not just a problem of “low sodium” — you don’t typically get hyponatremia by not eating enough salty foods. Hyponatremia is a relative disorder — the amount of sodium in comparison to the amount of water. There are actually 3 primary types of hyponatremia, each with different typical causes:

Euvolemic hyponatremia

Euvolemic hyponatremia can also be called dilutional hyponatremia, and is the kind we’re talking about. It’s typically caused by polydipsia — excessive thirst, causing you drink more water than normal. But again, this can also happen as a result of thinking that you can’t drink too much.

The ordinary treatment is to treat the cause — often diabetes, mental illness, or brain injury.

Hypervolemic hyponatremia

Hypervolemic hyponatremia occurs when both water and salt increase, but the water increase is relatively greater than the sodium. It usually happens as a result of health issues that cause water and salt retention, like heart failure or cirrhosis.

In those cases, treatment is usually fluid restriction and administering a diuretic, a medication that forces fluid to be excreted through urination, to remove body water.

Hypovolemic hyponatremia

Hypovolemic hyponatremia — if you have any knowledge of medical terminology — is the opposite of hypervolemic hyponatremia. In this case, both total body sodium and water have decreased, but the salt levels of have decreased comparatively more.

This type of hyponatremia happens when sodium-containing bodily fluids are lost — think vomiting and diarrhea during prolonged illness. It can also happen with some kidney disease and prescribed medications — like those diuretics mentioned earlier. Treatment varies by severity, but involves replacing both the fluid and sodium lost through administration of medications like 0.9% Normal Saline.

Preventing overhydration and hyponatremia

So since it’s been established that you can drink too much water — with potentially deadly consequences — how can you can avoid it? Drinking enough water, but not too much, is relatively simple:

• Drink according to thirst. Your body knows when it needs water, so drink when you get thirsty, not before. If you’re sedentary, shoot for the numbers mentioned earlier. If you’re active, use those numbers as a guideline, but expect to drink more (especially if you’re taking a diuretic). And time it according to feelings of thirst.

• Estimate hourly sweat loss. A slightly more complex method, if you exercise for prolonged periods, in hot or humid weather, or compete in sports, you can try this out. Weigh yourself before the exercise, drink according to thirst during the event, then weigh yourself afterward. Your goal is to be the same or slightly less weight — if you weigh more, than you drank more water than necessary. This strategy may more applicable if you compete in sports (i.e. football), where you have a scale available that you can use each hour to guide your fluid intake.

• Avoid excess fluid consumption. This one’s simple — if you’re not thirsty, don’t drink excess fluids. Otherwise, you might experience nausea or even vomiting. Of course, that doesn’t mean don’t drink any fluid at all, but simply don’t drink if you’re not thirsty.

Likewise, there are a few things you can keep an eye on as simple “markers” to determine if you’re drinking enough: if you aren’t thirsty (or often thirsty) or if your urine is colorless or faintly yellow — you’re likely drinking enough water.

Wrap-up

Despite common knowledge, it is possible to overhydrate. This can lead to as little as some confusion, to as far as coma or death. But, simple measures can be taken to ensure that you are both:

1. Drinking enough; and

2. Not drinking too much.

Essentially, listen to what your body is telling you. Water consumption is important to your overall health, and thus your body composition goals. Drink whenever you get thirsty, drink enough to support your activity levels — but don’t “over-drink.” You’ll thank us later.

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Matthew Seiltz is a writer and lifelong strength and fitness enthusiast. When not writing or working out, he can be found with a book or spending time with his wife and sons outdoors.

You’ve probably heard or read about how you can survive for weeks without food but that you can only survive for days without water. Your parents probably told you repeatedly when you were young to drink at least eight cups of water a day. Water is known to help cleanse out the toxins in your body and to quench your thirst on a hot summer day. But what role does water play when it comes to body composition?

While most of us are predominantly preoccupied with total body weight, body fat percentage, or even BMI, total body water and hydration status are often overlooked.

When was the last time you thought about getting enough fluids in your body to reach your health and fitness goals? 

Staying well-hydrated is not just important for survival. Your hydration status is equally as important as getting enough rest and quality food for muscle growth and improved physical performance. Moreover, meeting your daily hydration needs could be the difference between accomplishing your desired body composition goals and not seeing body composition improvements when you think you’re doing everything right.

In this article, we’re going to put a spotlight on the following:

• What body water is and why keeping an eye on your body water balance is important
  
  

• What happens to your body when you’re dehydrated

• Why it’s important to stay hydrated if you’re looking to build more muscle

• The link between dehydration and fat loss

• How much one should drink daily to stay well-hydrated

What is Body Water?

At one point, you’ve probably wondered what makes us truly human?

You’ll probably get various answers from people with different backgrounds. There’s consciousness, free will, having a set of morals, the idea of having a soul, and being fully aware of our own mortality.

Although these answers require further deep thought and investigation, one thing’s for sure: as much as two-thirds of your body weight is water.

Trivia: Ninety-five percent of the body of a jellyfish is water.

Even though much of our body is made up of water, the percentage of our body composition that is water changes based on our functional needs. Some of the essential functions of water in our bodies include the following:

• It’s a building block to almost every cell in the body.
  
  

• It regulates body temperature via sweating and respiration.

• Carbohydrates and proteins used for energy are transported by water in the bloodstream.

• It assists in the removal of metabolic waste, mainly through urination.

• It acts like a shock absorber to protect our brain and spinal cord.

• It makes up saliva and fluid that lubricates your joints.

The amount of water in your body depends on various factors including age, gender, physical activity, and even where you live. It’s often referred to as Total Body Water (TBW).

For example, infants are born with roughly 78% of their entire weight being water. By one year of age, TBW decreases to about 65% of weight. In healthy adult males, TBW averages 60% of their weight because they generally carry more lean mass. On the other hand, women will see that roughly 55% of their weight is TBW.

Most of this water comes from that lean body mass mentioned above. This includes your blood, organs, and muscle. Here’s a snapshot of the major body organs’ water content:

• Brain and heart – 73%
  
  

• Lungs – 83%

• Skin – 64%

• Muscles and kidneys – 79%

• Bones – 31%

Your TBW can be further segmented into two compartments: extracellular water (ECW) and intracellular water (ICW).

Intracellular Water (ICW)

ICW is the amount of water found in your cells. In healthy adults, ICW makes up two-thirds of your total body water. Essential cellular processes take place in the ICW, such as creating the energy necessary to fuel each cell for their specific functions.

Extracellular Water (ECW)

ECW is the amount of water located outside of your cells. It makes roughly a third of the total body water in healthy adults. ECW helps control the movement of electrolytes, delivers oxygen to the cells, and clears waste from metabolic processes.

In terms of body composition, an increase in ICW can signify increased muscle mass. On the other hand, an increase in ECW could indicate inflammation, fluid retention, or disease.  In fact, inflammation resulting from having too much visceral fat can trigger activation of the renin-angiotensin-aldosterone-system (RAAS) which in turn increases ECW. When activated, this hormone system acts to maintain blood pressure and fluid balance. However, when overstimulated, the RAAS can lead to symptoms associated with obesity, kidney disease, and the metabolic syndrome.

It’s worth noting that TBW is constantly changing with gains and losses of fluid even in healthy adults. The volume is regulated through a complex system of exchange of fluids, solutes, and ions within the compartments in the body — the RAAS and the ADH.

Here’s how the ADH system works when your body experiences a significant loss of body water:

1. The hypothalamus —the gland responsible for regulating our body temperature and triggering the processes that balance the fluids in our bodies—detects dehydration.

2. As a result, the hypothalamus signals the release of antidiuretic hormone (ADH) vasopressin which causes the kidneys to remove less water from the blood. This leads to peeing less and a darker, more concentrated urine. It also raises blood pressure.

3. Meanwhile, your brain also tells you that you’re thirsty, and once we sip on some water or consume something that’s made of water, TBW levels return to normal. The same mechanism happens when your body temperature rises being in a warm environment, working out, or fever. Body temperature goes down with sweating which in turns helps you cool off.

As for the cellular compartments, a water deficit leads to an increase in the electrolyte concentration in the extracellular compartment. This higher electrolyte concentration draws water from the intracellular compartment improve the electrolyte-fluid balance in the ECW, causing the cells to shrink.

The RAAS and ADH systems work interchangeably to keep our fluid balance on track and properly-timed because our brains, kidneys, various glands, and hormones work together to monitor the amount of water that you’re taking in and losing.

All of these are analogous to a radiator which heats a room. You set it to turn on at a certain temperature. When the room falls below that temperature the radiator turns on. When the room temperature increases, the radiator turns off. In this case, the RAAS activates when the room temperature is too hot (fluid is too high) and the ADH activates when room temperature is too low (fluid reduced).

In short, your body is smart and sensitive enough to detect irregularities and compensate for losses and gains to make sure that everything’s well-balanced.

What Happens to Your Body When You’re Dehydrated

Fluid gains and losses throughout the day (when you breathe, sweat, and pee) are regulated by the hypothalamus, the renin-angiotensin-aldosterone system, and kidneys.

Dehydration doesn’t occur until you’re losing more water than you can replace — frequent episodes of diarrhea and vomiting, having too much alcohol the night before, or sweating and peeing like crazy.

When dehydration sets in, you’re likely to experience a wide range of symptoms. Early signs and symptoms include dizziness, headaches, dry mouth, and cool skin. When not addressed in the early stages, dehydration could lead to a lack of urge to pee. Remember that time when you were out hiking and you haven’t peed in hours?

Dehydration can lead to long-term health consequences as well. High blood pressure is also common in people who are chronically dehydrated. When the body’s cells are devoid of water, the brain sends a signal to the pituitary gland to secrete vasopressin (a chemical that causes constriction of the blood vessels), which in turn causes blood pressure to rise. Chronic elevations in blood pressure can eventually lead to heart failure. As blood vessels narrow, oxygen and blood supply to the brain are also put in jeopardy resulting in migraines and significant dips in concentration.

Why It’s Important to Stay Hydrated When You Want to Gain Muscle Mass

Research studies have shown that when cells lose water (and thus volume), protein production can slow down and protein breakdown speeds up. However, it’s worth noting that these studies are done in-vitro (isolated in test tubes rather than an animal or human) and further research is required on the relationship of hydration and its impact on muscle mass breakdown.

What might this mean for the average person? Forgetting your water bottle at home before leaving for the weight room could mean leaving muscle gains on the table due to poor performance.

For instance, when you’re moderately dehydrated (approximately 3% of body weight), exercise performance may be impaired, particularly with repeated bouts of anaerobic exercises (e.g. weight lifting, sprinting). As a result, it increases demand for aerobic metabolism. This is further supported by another study concluding that blood flow to the exercising muscles (in prolonged exercise) declines significantly with dehydration.

It seems like dehydration can also increase your likelihood of injury.

Research findings by the Chicago State University suggested that dehydration of 2.9% body mass decreases the ability to generate upper and lower body strength. The researchers recommended that coaches and athletes must understand that sports performance requiring strength and power may be impaired by inadequate hydration resulting in increased susceptibility to injury.

Finally, dehydration may cause stalled muscle growth.

A study performed in ten-weight trained males reported that passive dehydration resulting in approximately 1.5% loss of body mass, as a result of water loss, decreases muscle strength of one rep max bench press. When muscle endurance and power are compromised due to dehydration, you’ll likely end up not pushing for more reps in the weight room, making your workout less effective.

In summary, dehydration could potentially lead to stalled muscle growth, possible muscle mass breakdown, increased risk of injury, and impaired exercise performance.

Can Dehydration Hinder Fat Loss?

Now that you’re aware of the importance of being well-hydrated to gain lean body mass, you’re probably curious if your hydration status can also impact fat loss efforts.

In a study by published in Annals of Family Medicine, the researchers found out that people who are obese and have a higher body mass index or BMI (although BMI has its own limitations) are more likely to be inadequately hydrated and vice versa. The researchers further concluded that—although the correlation requires further probing— their findings should encourage clinicians to consider hydration as a cornerstone of a weight-loss diet.

Meanwhile, studies have found that increasing water intake can lead to greater weight and fat loss than dieting alone. Overweight and obese adults were assigned a reduced calorie diet where one group was required to drink 500ml of water prior to every meal and the other group had no fluid consumption requirements. At the end of 12 weeks, the water drinkers were found to have a 44% greater rate of weight loss!

While further research is required, more focus on hydration appears to help people who want to speed up their fat loss efforts.

How Do I Know If I’m Dehydrated?

Before learning how much fluids and water you need to stay well-hydrated, it’s equally important to know if you’re already dehydrated or not.

Besides feeling thirsty and tired, here are some signs of fluid deprivation that some people overlook:

• Darker colored urine (medium yellow to a brown range) or lack of urine

• Headaches that worsen and turn into migraines

• Confusion and inability to concentrate

• Irritability

Your Game Plan: How to Stay Well-Hydrated

As for how much water and fluids to drink, it is important to ensure that you’re getting enough as everyone’s hydration needs differ depending on a number of factors. Age, climate, activity level, and existing health issues can all impact daily fluid requirements.

The Institute of Medicine recommends that women and men consume roughly 2.7 liters (91 ounces) and 3.7 liters (125 oz), respectively, of fluid a day. This may sound like a lot of water, but it is important to note that these fluid recommendations include intake from both food and beverages. In fact, food is estimated to contribute to 20% of our fluid intake alone!

In a nutshell, if you’re having your daily intake of fruits and vegetables and drinking fluids, you’re probably getting the water you need.

However, pay more attention to your hydration needs and fluid-guzzling habits when you’re involved in prolonged workouts or hard exercise, and when you’re sick resulting in frequent bouts of diarrhea and vomiting.

In these situations where we are losing excess water, it is often recommended to consume beverages that offer more than just water. For instance, ultra-endurance athletes are encouraged to up their fluid intake and make sure to opt for drinks with electrolytes. Sodium is necessary during recovery in reducing urinary output and increasing the rate of fluid balance restoration so these types of drinks offer benefits that water alone cannot.

Watch Out for Overhydration

Although dehydration is a serious concern, overhydration or hyponatremia is something to watch for when considering fluid and electrolyte replacement.

Hyponatremia is an electrolyte disorder in which plasma concentration of sodium is too low. Most cases of hyponatremia are induced by an increase in total body water. Many instances of hyponatremia have occurred because of drinking too much water.

In fact, the New England Journal of Medicine reported in a study of Boston Marathoners that hyponatremia has emerged as an important cause of race-related death and life-threatening illness among marathon runners. The researchers further found that sudden weight gain during the race (which correlated with excessive fluid intake) was the strongest single predictor of hyponatremia.

Proper Hydration May Be the Missing Link to Improving Your Body Composition

Your hydration status and meeting your daily fluid needs are equally as important as getting enough sleep and eating right in helping improve your body composition and staying healthy.

Not drinking enough water before your morning jog, forgetting your water bottle before spin class, and binging on alcohol the night before you do serious legwork are surefire ways to dehydrate and hinder progress in your body composition goals. Why not drink up some water or have a quick fruit-filled snack?

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Kyjean Tomboc is a nurse turned freelance healthcare copywriter and UX researcher.  After experimenting with going paleo and vegetarian, she realized that it all boils down to eating real food.