Water is the largest component of our body. In general, 60-70% of the total body weight of lean adults and 45-55% of the total body weight in obese adults is water.
Water is necessary for digestion, absorption, and excretion of substances of our body and plays a key role in the structure and function of the blood circulation system and the transport of nutrients in the body.
Dehydration of 20% may lead to death. Dehydration of only 10% may lead to damage to vital organs of the body. Mild dehydration (1-2%) can lead to loss of cognitive function, unconsciousness, increasing heartbeat, and decreasing athletic performance. Elderly people feel less thirsty, so they are at higher risk for dehydration.
Healthy adults can survive for 10 days and healthy children for only 5 days without water. However, these people may survive for weeks without food.
Dehydration takes place through the kidneys, gastrointestinal tract, skin, and lungs. But some factors may cause decreasing water in our body that we can not feel. Such as high altitude, low humidity, and high temperatures that can play a role in expelling water through the lungs and sweating.
Dehydration can cause headaches, fatigue, loss of appetite, distraction, and confusion, poor skin tone, skin rash on the forehead, thick urine, decreased urine output, sunken eyes, dry mouth, and nasal mucosa, changes in blood pressure by standing and increases heartbeat.
Factors such as age, calorie intake, and weight are usually considered to estimate the water and fluids needed. The necessity of 8 glasses of water is not enough. The body is not ready to store water, so the amount of water that is excreted in 24 hours must be replaced to maintain good health.