Hydration and water intake : How it happens and how much do we need?

Hydration is the process of causing something to absorb water. In our case it is the process of our bodies absorbing water. We all know that water is vital to our survival; we would perish without it. But how much water do we need on a daily basis and how do we absorb it?

When talking about the human body we have two methods of absorbing water into our systems.

The first method I will touch on is dermal absorption. Simply put, we can achieve water absorption through our skin. This accounts for a small amount of our body's hydration efforts but it is still present. Small pores in our skin allow water to seep in or pass through the cells via permeation (the penetration of a liquid or gas through a solid). Submerging the body in water either by taking a bath or going for a swim will be the most effective method to achieve this absorption but you can also apply your favourite hydrating body lotion.

For more effective hydration, one would consider the second method which utilizes the digestive system. This is of course the system we use to the most to hydrate when we drink water!

The main contributor to absorption is the digestive system which is responsible for the majority of the absorption in our body. Multiple organs in this system contribute to various amounts of water absorption throughout the digestive tract. These organs take turns absorbing, expelling and reabsorbing our body’s water content to help us digest nutrients and eliminate waste. The majority of the reabsorption occurs in the large intestines before the colon. If this system is operating properly it will be our main source of hydration assuming we are intaking enough water to begin with.

If the system is not working properly it could lead to more severe problems such as dehydration which has a snowball effect on the rest of our body’s systems. When you have bowel issues such as diarrhea this is usually caused by a “bug” that affects the water reabsorption in your large intestine.

So, how much water intake is enough?

This question is always asked in the fitness industry by athletes and the general population alike: “How much water should I drink in a day?”

The answer is: “it depends”. Daily water intake depends on a number of different factors and these factors change on a day to day basis. It depends on your body size, sex, nutrition, activity level, previous day hydration, weather, medication, illness and more. Trying to accurately tell someone just how much water they should have each day is like trying to hit a moving target. We might be able to guess right every once in a while but, unfortunately, most of the time most individuals are below what they should be consuming.

However research does suggest target ranges for “average” healthy adults in order to maintain healthy functions of our systems. This target is between 2.7 L and 3.7 L(1). It is important to remember this changes daily based on a number of factors, as previously indicated, and also includes the amount of water we get from other sources such as other drinks and food.

Try to aim for 3-4 large glasses or about 8 cups throughout the day or fill a large water bottle and drink that over the course of the day in addition to any other drinks you may have (ie. coffee, tea, smoothie, milk). It may seem like a lot of water to drink and that you will spend a lot of time in the bathroom but that is not a bad thing. Urine colour is a great indication of our hydration levels. Tip: drink until you notice a clear yet slightly yellow hue!

1. Sawka, M., et al, Human Water Needs, Nutrition Reviews, Volume 63, Issue 01, Pgs. S30-S39, June 2005.

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