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InBody USA - What You Need to Know About Hydration and Your Body

February 5, 2020



What Makes Up Your Body Water | Imbalances In Your Body Water | Dehydration and Overhydration | Finding Your Balance With Hydration


Water is a major part of your body: they make up 79% of your muscles, 73% of your brain, and even 31% of your bones. Overall your body weight can be 45-65% water. Your body water percentage is influenced by your age, gender, and fitness level. Even though you are made up of mostly water, how much do you really know about the effect this major element has on your body?


For example, did you know your hydration status is equally as important as getting enough rest and quality food for muscle growth and improved physical performance?

Read on to learn more about body water, the effect of dehydration and overhydration, and tips to keep you in balance. 

Body Water, Defined


Your body water can be found inside not only in your blood, but in your muscle tissue, your body fat, your organs, and inside every cell in your body.  


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.


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


Extracellular Water (ECW)

Extracellular water is the water located outside your cells.  The water in your blood falls into this category. Roughly 1/3 of your fluid is attributed to ECW, and this water is found in your interstitial fluid, transcellular fluid, and blood plasma.

Extracellular water is important because it helps control the movement of electrolytes, allows oxygen delivery to the cells, and clears waste from metabolic processes.


Intracellular Water (ICW)

Intracellular water is the water located inside your cells.  It comprises 70% of the cytosol, which is a mix of water and other dissolved elements.  In healthy people, it makes up the other 2/3 of the water inside your body.


The intracellular water is the location of important cellular processes, and although it has many functions, a very important one is that it allows molecules to be transported to the different organelles inside the cell.  Essentially, the Intracellular water picks up where the Extracellular water left off by continuing the pathway for fuel to be transported to the cells.

Balance is the Key


When it comes to your body water and you, the most important thing to strive for is balance. Your Intracellular fluid: Extracellular fluid must remain at the same levels with respect to each other.


A healthy fluid distribution has been estimated at a 3:2 ratio of ICW:ECW. If your body water falls out of balance, this can signal changes in your health and body composition. Whether these changes are positive or negative depends on which type of water becomes unbalanced.


Positive: Increased  ICW

Having slightly more ICW than normal isn’t necessarily a bad thing. In fact, it can signal positive changes in your body composition. 

Increased muscle mass is due to the enlargement of the number and size of muscle cells.  When the muscle cells become enlarged, they are able to take in (and require) more ICW in order to power their cellular functions.  Research has shown that resistance exercise can lead to increased intracellular water in humans as a result of increased Lean Body Mass.


Negative: Excess ECW

If your ECW increases in relation to your ICW, this is something you should take special note of.  Unlike ICW, you do not want to see your ECW increasing beyond normal levels. Excess ECW can indicate health risks, including:


Inflammation

During inflammation, the body sends additional blood flow to the damaged area.  This causes an increase in extracellular water in a particular area. Inflammation occurs when part of the body gets damaged or bruised and is a normal bodily response to injury.  This is called acute inflammation and is a temporary increase in ECW.


Chronic inflammation, however, is something more serious that isn’t always readily detected. It is marked by long-term swelling/ECW increases caused by cellular stress and dysfunction. Chronic inflammation can lead to serious diseases if allowed to persist over time, including renal failure, cancer, and heart disease. including renal failure, cancer, and heart disease.

Obese individuals are characterized by having too much body fat, which among other things, leads to body water disruption due to excess ECW.  This is because excess visceral fat can trigger production hormones that can lead to the disruption of a bodily system called RAAS.  This excess ECW causes stress in the body due to its effects on the internal organs, which can exacerbate obesity and cause a dangerous cyclic effect.


Renal Disease (Kidney Failure)

One of the kidneys’ major functions is to filter your blood and remove toxins produced in the body.  One important substance that the kidneys filter out is sodium, an element that is found in salt.


When your diet includes more sodium than your kidneys can filter out, which occurs in people who have failing kidneys, your extracellular water levels will increase.  In some cases, this increased extracellular water shows in visible swelling throughout the body and is a condition known as edema. Edema can cause additional strain on the body by contributing to weight gain, blood pressure, and other complications.


Determining Balance

Since it’s so important to keep an eye on your fluid balance, you’ll need to know how you can determine yours. There are two major methods to measure and determine your fluid levels.  These are the dilution method and the BIA method.


The dilution method involves drinking a known dose of heavy water (deuterium oxide) and allowing it to distribute around the body.  Once the water has had time to settle, the amount of heavy water is compared with the amount of normal water. The proportion will reflect the amount of total body water.  To determine ECW, sodium bromide is used instead of heavy water.


The dilution method is recognized as a gold standard for measuring total body water; however, these tests would need to be done at a hospital under the guidance of a trained physician.  This test takes several hours to complete during which any fluid of any type going in or out of the body has to be carefully recorded.