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Water and Health; Functions in the Body and Daily Needs

Importance of Water for Health

Humans can live for 5 minutes without breathing, six days without water and 40 days without eating. Water is the most critical food for life. The relationship between water and health is extremely important.

Although it varies slightly with age and gender, approximately 65% of an individual’s weight is water. When evaluated on an adult individual weighing 70 kg, this individual’s body contains about 45 kilograms of water.

  • When water loss reaches 1-1,5% levels, thirst, irregularity in movement, loss of appetite, increase in rectal temperature, impatience, fatigue and increase in heart rhythm are observed.
  • When water loss reaches 6-7% levels, headache and difficulty in breathing, speaking and remembering are observed.
  • If the individual loses 8% of the water in his body, that is, if he fails about 3.6 kg of water, irregularities in body functions begin and usually result in death.

The Roles and Functions of Water in the Body

1. Water is used as a building material in the body. Water constitutes approximately 75% of the muscles, 25% of the bone tissue, 20% of the fatty tissue and 10% of the dental dentin tissue. Therefore, water consumption significantly affects body structure.

2. Water acts as a carrier in the body. In cell biology, the nutrients, hormones, enzymes and wastes produced by the cell’s activities are carried by water. Likewise, like saliva, it also acts as a water solvent and carrier in our body’s secretions. In terms of tissue biology, water also acts as a carrier in the digestive and excretory systems. Without water, digestion and excretion are unthinkable.

3. Water plays a vital role in regulating body temperature. When the body rises above the average temperature, excess heat is expelled. We sweat when we exert intense effort because the body tries to throw out the excess heat with water.

The individual wants to drink cold water in hot weather due to the body’s desire to balance the heat with the cold water taken. Likewise, the desire to drink hot beverages in cold weather stems from the body’s desire to maintain the heat balance with the heat of the liquid.

4. Water acts as a buffer against pressure and impact. Water prevents the negative effects of wear and friction by providing lubrication of bone joints, moving organs such as eyes and eyelids and internal organs. On the other hand, as in the example of the brain and fetus, it wraps around the organism’s structures and undertakes a protective role against possible external impacts.

How Much Water Should You Drink Per Day?

“How much water an individual should consume” can change depending on factors such as the individual’s gender, age, body structure (weakness or overweight), illness, pregnancy, effort, climate and environmental characteristics, the content of the foods consumed and the calories of these foods.

In water consumption, care should be taken to preserve the body’s amount of water and consume enough water to be balanced with the amount of water removed from the body.

When the density of blood plasma increases by 1%, the thirst center in the brain is stimulated and a feeling of thirst occurs. Another point to be considered in terms of water balance is urine color. Light yellow color is a standard color. The darkening of the color and the increase in darkness are an indication that the body is not getting enough water.

The body obtains water from 3 different sources. The primary sources of water are drinks and food. Another source is water formed in the body due to metabolic activities. As a result of metabolic conditioning, approximately 300 mL of water is produced per day.

In general, the body provides 50% of its daily water requirement from drinking water and water-based beverages, 35% from food and 15% from water produced due to metabolic activities.

The body needs a certain amount of building blocks and energy to maintain its basic life activities even if it does not perform any action and rest (basal metabolism).

In general, a healthy adult individual burns approximately 1000-2500 calories per day for basal metabolic activities. The body’s water requirement is about 1 mL of water for each calorie consumed.

Therefore, the amount of water a healthy adult individual needs on a resting time is 1.5-2.5 liters. There is a wide range of 1.5 and 2.5 liters because the individual’s basal metabolism differs according to gender, age and body structure. However, it should not be forgotten that this amount is the amount needed if no action or activity is taken as mentioned.

Going through examples will provide a better understanding of this subject. Depending on gender, age and body structure, the amount of energy consumed per day by an individual working at a desk job and accordingly the amount of water he needs daily is as follows;

water needs in desk jobs
water needs in desk jobs

The table in question presents data on individuals working at a desk job. Naturally, situations such as exertion and sports status, mobility and intense mental activity in daily life will increase the amount of energy that the individual spends and the amount of water he will need.

water loss in physical activities
water loss in physical activities

Based on the information given, let’s examine the amount of water that an individual should consume through an example; The table shows that a healthy 35-year-old man, who weighs 80 kilograms and works at a desk, needs approximately 2.2 liters of water as a result of one day’s activity.

Suppose this individual performs activities such as walking for 1 hourcooking for 1 hour and watching TV for 2 hours in addition to his job. In that case, his body will lose approximately 2 liters of water due to these activities.

Therefore, the daily water requirement of the individual will be 4.2 liters in total. Since the body will meet 50% of this need from water and water-based drinks, 35% from food and 15% from water produced in metabolism, this individual should drink at least 2.1 liters of water for that day.

Here, it is necessary to pay attention to the following in terms of nutrition. As it is known, water-based beverages such as tea and coffee are very popular and consumed quite a lot.

However, it is not appropriate to consume these beverages to meet water. Because these drinks show a high diuretic effect, it has diuretic effects. Drinks with a high diuretic effect can quench the feeling of instant thirst, but they cause more water to be removed from the body than the amount drunk. A healthy individual should drink as much water as the tea and coffee he drinks not to disturb the body’s water balance.

Another critical issue is the nutrition program. The habit of eating foods with low water content, such as fast food, causes the individual not to get enough water from food. Therefore, individuals fed such low-water foods should drink more water and water-based beverages.

All these data and evaluations are presented on healthy individuals. However, it should be known that the need for water will increase even more in cases of illness such as vomiting and diarrhea, pregnancy and hard working conditions.


Here are some of the articles that might interest you;

Quality Characteristics That Drinking Water Should Have 

Water in Foods; Forms, Characteristics and Importance

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