No matter how solid it looks, the human body is made mostly of water. Water is the most abundant molecule inside and outside of our cells. When we are six months old, almost 74% of our body is water. The amount decreases as we get old, but still constitutes about 50-60 percent of our body weight. There is almost no chemical reaction in our bodies that takes place without the presence of water. Due to its importance, our body has a very efficient mechanism of keeping water at a normal level. These mechanisms control both the intake and the output of water. We have a daily water loss due to physiologic activities like sweating and urination, and therefore, we need a constant daily intake of water to make up for this loss. To put it simply, we need to drink water every day.
Regulation of water
The body controls the water at two points: the water entrance and water exit. Water usually gets out of the body through the functions of respiration, sweating, bowel movement and, most important of all, urination. The main route of water entering the body is eating and drinking. When we are in need of water, the body limits the output of fluid. For example, urination or sweating may decrease. But the loss of fluid can never stop completely. Even in the worst water deprivation situation, we still lose some water. Therefore, our health depends on how much water we drink. The thirst mechanism controls the intake of water into the body.
Thirst and daily water intake
Thirst is the language of the body to tell us when it needs water. Apart from the kidney, the thirst mechanism is our most important tool to balance water status in the body. Whenever the volume of water comes down to a certain level or the concentration of salt increases, a complicated mechanism is kicked off that leads to the familiar sense of thirst, which guides us to drink water. However, not all the water we drink is in response to the thirst stimulus. Paradoxically, we consume most of our daily fluid when we are not thirsty. Some of it comes from liquid foods, like soup, but most come from drinking out of habit or pleasure, like drinking coffee, tea or alcohol.
What is the recommended daily water intake?
It is not easy to determine how much water each person needs per day. It depends on many factors like age, sex, metabolic status, climate and physical activity. However, efforts have been made to determine an “adequate” intake level of water. It is the amount of total water, in any form and not just plain water, that if we receive, we are probably safe from the adverse effects of dehydration. According to The Office of Dietary Supplements, for HEALTHY PEOPLE, the adequate intake level of fluid is 3.7 lit/day for men and 2.7 lit/day for women. For men, 3 lit/day should come from water and other beverages. And for women 2 lit/day needs to be from water and beverages. The rest can come from food. This amount could change if people have health conditions.
How much can we trust our thirst?
Now the question is: should we be alert and conscious, all the time, of our daily water intake? Or we need to trust our thirst feeling and simply drink water whenever we are thirsty? We know that the sense of thirst decreases with age. So, older men and women need to be more careful about their water intake. But what about other people?
For most other people, the thirst mechanism is very efficient and reliable. The only point is that we may ignore it. In the hasty lives that many of us have, it is not rare to push our senses aside while jumping from one daily activity to the next. We are not usually mindful of what we see or hear around us. We are not generally aware of our postures at our desks. We lose contact with our senses. In the same way, we may be ignorant of our sense of thirst. Our sense of thirst is shrewd enough if we stay in touch with it.
What we need is adding a tinge of mindfulness to everyday life.
