Water requirements
It makes up around 60% of the human body. All nutritional elements are dissolved in it. All waste products are found in it and eliminated through it. Water is truly a vital element, and must be constantly replenished, hence the need to drink regularly. We can go without eating for several days or even weeks (the body then lives on its reserves), but we can't go without drinking for more than a few days: a water deficit of 5 to 10% leads to great weakness, and a deficit of 20% is fatal! As for chronic water shortage, it can lead to kidney stones, constipation, wrinkled skin, fatigue, a feeling of malaise, headaches, a dry tongue, etc.
To enable the hormonal mechanisms to regulate the volume of water in the body so that it always remains stable (overflow being evacuated in the urine), we need to ingest as much water as we eliminate, i.e. an average of 2 to 3 liters a day. Elimination takes place via the kidneys and urine (1 to 1.5 liters per day), as well as perspiration (evaporation through the skin) and perspiration (0.5 to 1 liter). In the event of extreme heat or physical exertion, this quantity is much higher, and can amount to several liters. Finally, a certain amount of water is also eliminated in the stool (100 to 200 ml), which explains the risk of dehydration in the event of severe diarrhea. It is generally considered advisable to drink around 1.5 liters of water a day, in addition to the 1 liter provided by food (via fruit, vegetables, soups, yoghurts, etc.).
Did you know that you should always drink before you feel thirsty ? The sensation of thirst alerts the body to a lack of water, but it takes a while for the brain to transmit the information... In particular, it's important to drink a lot at breakfast, as all metabolisms continue during the night and the heat of bed dehydrates. You then need to drink throughout the day, before, during and after meals, and the saltier you eat (which isn't particularly recommended), the more you need to drink at the same time, otherwise you'll experience intense thirst in the hours that follow.
