Water and the Impact on our Body’s Function

Sarah Duckworth, PT, DPT

January 01, 2020

Water and the Impact on our Body’s FunctionDid you know that water is one of the most critically important elements in our bodies?

Water is more than a chemical compound of two Hydrogen atoms bonded to an Oxygen atom. It is a critical component to life. A typical male’s water composition is 60% of his body weight, whereas a female’s water composition is closer to 55% of her body weight. Infants water composition is approximately 75% water, due to their smaller size. Water is in every cell of our body, creating the primary building blocks of matter for our organs, tissues and cells. Water’s functions and purpose in our bodies are numerous, such as:

  • Regulating our body temperature
  • Serving as a shock absorber
  • Building material for our cells
  • Solvent of cellular fluid
  • Removes wastes and toxins from the body
  • Aids with digestion of food

Our brain is composed of 70% water, assisting with all neurological functions necessary to survive. Water helps our neurons create signals to send to the rest of the body as well as creating new connections and memories for things that have been learned. Our bodies cannot produce sufficient water through metabolism or break down enough water from our food intake, so we must replenish our supply through fluid intake.


Hydration is simply achieved, when an individual is able to maintain appropriate water balance. To be able to achieve this, we have to replenish the amount of water that is being used in our body for daily functions. There are several different suggestions for finding the “right amount of water” one should drink, but they are dependent on many factors. These include: air temperature, body weight, food intake, sweating and activity level. Our bodies are continuously losing water from the skin, lungs, kidneys, and constantly through our cells, making rehydration a constant necessity. Food only accounts for ⅕ of the total fluid intake our body’s need to rehydrate, so the remaining amount needs to be addressed through fluid ounces.

The recommended intake varies from source to source, but most often the suggestions include:

  • Drinking 6-8 glasses of water a day: 48-64 ounces
  • 3-4 glasses should be consumed during the school or work day

Urine ChartResearch has been completed on individuals to determine the best way to measure hydration levels in humans. Across these studies, a urine color chart was created to help people objectively identify their current hydration status without continuously relying on laboratory measures. The creators of this chart advise people to use a physical handout of the chart to provide the best accuracy, as color variation in computer screens can modify the selections. While looking at the color of one’s urine, it is ideal to see more of a lighter yellow color, indicating optimum hydration status. The darker the urine, the more dehydrated one truly is.

Using a urine color chart can be helpful to identify the amount of water you or your children may be taking in, without having to track or monitor how many fluid ounces are being drunk. The more you are aware of what is going on inside your body, the stronger your understanding will be on how to fix or change it.

What Happens To Our Bodies When We Are Not Hydrated?

Previously, it was thought that a loss of 2% or more of our bodies water weight would result in impaired cognitive function, but now it is being measured that cognitive function can be impacted with only a 1% body water deficit. This was often thought to be more of a concern with higher level athletes, but research is now indicating the implications of dehydration on our cognitive performance, especially in children.

When our bodies do not have the appropriate amount of hydration, our brain and neurological system are not able to function appropriately to be able to send and receive information. At the first sign of thirst, your body is already experiencing:

  • Up to a 10% deficit within memory, concentration and attention
  • Dizziness
  • Dry mouth
  • Headache
  • Fatigue
  • Cramps (muscle)

Dehydration activates the body's thirst response. When attempting to rehydrate your body, your perception of thirst may disappear before the appropriate water balance is reached. A survey was performed with 3,003 Americans, identifying that 75% of participants had a net loss of fluid, leading to chronic dehydration. While the individuals were drinking several glasses of water, they were additionally consuming beverages that were negating the effects of water (i.e. high sodium intake, alcohol or caffeinated beverages).

Our children and elderly are at increased risk for dehydration effects. Children are affected secondary to the dependence on others to meet their needs and they are more vulnerable to imbalances in fluids and electrolytes. Surprisingly, only 15% of children consume enough water during their day. This is related to restrictions in school and limited access to water throughout the day. Research has been completed on school aged children, to study the effects of water intake, dehydration and cognitive status. It was concluded that a child’s ability to attend to a task or complete a cognitive skill was greater when provided with continued water access in the day.

Dehydration Effects

In whole, our society is dehydrated and under-educated on the importance of water on overall cognitive and physical limitations. If you or someone you know happen to be suffering from any of the above impairments, attempt to monitor and likely increase water consumption to see if those symptoms improve.


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