Drinking is the act of consuming water or a beverage through the mouth. Water is required for many of life’s physiological processes. Both excessive and inadequate water intake are associated with health problems.
A daily intake of 3-6 liters of water is required for the normal physiological functioning of the human body, depending on ambient weather conditions and diet (especially salt and sugar intake). The absolute minimum over the long term is about 1.6 liters (600 ml for urine, 200 ml for fecal losses, and 800 ml for losses via the skin and lungs). This includes water contained in food (i.e., it is not essential to actually drink 1-2 liters of water a day for survival, though it is often recommended for good health).
The sensation caused by dehydration of the body is called thirst. The sensation of thirst is a dry feeling in the back of the throat and an intense desire to drink fluids. Thirst is regulated by the hypothalamus in response to subtle changes in the body's electrolyte levels, and also as a result of changes in the volume of blood circulating.
Role in disease
Polydipsia is the medical term for the desire to consume large quantities of water and may be a sign of various diseases (Diabetes Mellitus, Diabetes insipidus, and some psychiatric conditions).
Much of the world's disease is caused by the lack of clean drinking water. Lack of water in diet will eventually cause death by hypernatremia and dehydration, particularly when sweating consumes much of the body water. Unclean and unsanitary water can contain many bacteria and parasites that would otherwise be absent in clean water. Studies show that in some developing countries more than half of the population does not have access to safe drinking water.
It is also possible to overhydrate, which sometimes happens with athletes who consume too much water, thereby diluting the concentration of salts in the body. Overconsumption of water can be a sign of disease and/or mental health problems(e.g. damage to the hypothalamus), as stated above.
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