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Not drinking enough can get you dehydrated


Our body is mainly composed of water. Drink enough water is essential to stay healthy and hydrated throughout the day

Water is a key nutrient

Water is the main component of the body: it represents around 60% of the weight of an adult’s body. A little more in infants (~75%), and a little less in elder persons (50%) (1).

Water, present in each cell and organs of the human body, plays several key roles. It acts first as a building material. Water is also a solvent, a reaction medium, a reactant and a reaction product. It helps to keep the body at the right temperature, through its evaporation at the surface of the skin. Moreover, water in the body transports nutrients to cells – it is the major component of blood (blood is 92% of water). Therefore, it maintains vascular volume and allows blood circulation which is essential for the good functioning of the different organs of the body. Water also helps remove waste products from the body, and helps it stay hydrated (1)

In other words, not drinking enough water may, sooner or later, lead to dehydration. That is how important water is!

What does “not drinking enough” water mean?

An individual’s water needs depend on his age, his gender, the climate, his physical activity… (1-2). However, there is a recommendation: it is estimated that a healthy sedentary adult, living in temperate climate, should drink in average 1.5 liters of water per day (1).

What happens if you don’t?

An insufficient water intake disturbs the water balance. Indeed, to maintain the water balance, the water inputs must be equal to the equal outputs. Water intakes are composed of: the water you drink (~ 1.5 liter per day*), the water you eat (on average 675 ml per day) and the water your body produce (around 300ml per day).

Water outputs include: the water you lose via urine (around 1.6 liters per day), the water lost through the skin (approximately 450ml per day) and the lungs (~300ml/d), and finally the water in the feces (~200ml/d). (1)

When you maintain the water balance, you stay well hydrated. On the other hand, if the water intakes are lower than the water losses, you can experience a hydration deficit and thus one step further becoming dehydrated.

*For a healthy sedentary adult living in temperate climate

What are the consequences of the dehydration?

Let’s specifically talk about people who do not drink enough every day : For instance, they drink 1 liter per day instead of the recommended 1.5 liter for a healthy sedentary adult living in temperate climate. Let’s have a look at the consequences on short, medium and long term…

Thirst and dry mouth feeling. Indeed, any decrease in blood volume caused by an insufficient hydration leads to the activation of receptors located in the wall of the vessels, as well as the emission of a signal that is going to stimulate the thirst center in the brain (3). Concerning elderly persons, the thirst feeling is often altered because of the aging process (4).

Other signs of mild-to-moderate dehydration. These persons may feel tired,  or have muscle weakness… (1)

Some talk about drier and wrinkled skin; others affirm it increases the cardiovascular risk, but that has not yet been proven.

Tips for drinking enough water, every day :

  • Start the day with a big glass of water.
  • Drink during and between meals.
  • If possible, always have a bottle of water at your fingertips. When you see it, you will remember to drink!
  • Do not wait for a feeling of dry mouth or thirst to drink water.
  • Set an objective: drink 8 glasses of water* per day!

As discussed above, not drinking enough water may lead to insufficient hydration or one step further to dehydration. So let’s enthusiastically drink your 8 glasses of water* every day, and appreciate them, with the feeling to indulge yourself!

*For a healthy sedentary adult living in temperate climate; 1 glass = 200 ml
1- Jéquier E, Constant F. Water as an essential nutrient: the physiological basis of hydration. Eur J Clin Nutr 2010, 64: 115-23.
2- Dietary Reference Intakes – The essential guide to nutrients requirements. Institute of Medicine of the National Academies, Washington, DC, 2006, p.543
3- Ganong WF et al. Review of medical physiology. 22nd edition Lange science 2005
4- Philips PA et al. Reduced thirst after water deprivation in healthy elderly men. New Engl J Med 1984; 311: 753-9.
5- Popkin M et al. Water, hydration and health. Nutr Rev 2010, 68 (8): 439-58
By Laurence Plumey

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