We often hear the recommendation to drink two litres of water a day (about eight glasses), both from ordinary people and from professional fitness trainers or even nutritionists. Most firmly believe that consuming lots of clean drinking water is the first rule of healthy eating to follow by default. However, nothing is so simple, and modern nutritionists confidently say that there is no need for health to pour in an additional fluid forcefully. So how much water is necessary to drink daily. Let’s figure it out.
The statement that for health a person needs to drink at least two litres of clean water every day (without taking into account tea, coffee, juices and other drinks) or 8 glasses was made more than 70 years ago, in 1945, by the doctors of the American state organisation Food and Nutrition Board. So this recommendation underlies all tips to drink two litres of water a day.
At that time, doctors and nutritionists believed that each kilocalorie of food eaten for successful digestion requires about 1 gram of water, given that the average daily caloric intake rate is about 2000 kcal. That is exactly equal to two litres of water per day, which has to be consumed to stay healthy.
However, it is vital that the National Academy of Sciences’ Institute of Medicine(the successor to the FNB) decided to revise and add clarifying details to the existing recommendation in 2004. The organisation said that adult men needed about 3 to 3.7 litres of water for proper metabolism and women required about 2.7 litres of water.
The recommendation also had a significant amendment. Scientists separately stressed that it means pure water as well as any other liquid including that consumed in the combined food. Fruits, juices, variations of food, and other beverages also cover the daily demand for water in most cases. Therefore, calculating how much water is to drink a day, take into account all the different types of foods.
It is also interesting that numerous scientific studies have confidently proved that there is no connection between the additional daily consumption of two or three litres of clean drinking water and the improvement (or deterioration) of kidney or liver functions, as well as the cure or development of any chronic diseases.
Without a doubt, if a person runs a marathon distance in the heat or actively takes whey protein in powder, then the body needs additional fluid. However, it is impossible to say unambiguously how much water should a man consume daily.