Do you really need to drink two liters of water a day? New study says no

It is a commonly held idea, often recommended by doctors and experts, that a person should drink at least two liters of water every day to stay healthy and hydrated. However, new research has found that the recommended eight glasses of water a day may be too much. While it’s not exactly harmful, it’s also unnecessary in most cases.

Scientists at the University of Aberdeen recently teamed up with other researchers to understand how much water people really need to drink. They looked at 5,604 people from 23 different countries, aged between eight days and 96 years, BBC reported.

The survey findings published in Sciencestated that people only need about 1.5 to 1.8 liters per day, less than the two liters usually recommended.

In the study, people drank a glass of water in which part of the hydrogen molecules had been replaced with a stable isotope of the element deuterium, which occurs naturally in the human body and is completely harmless. The elimination rate of the extra deuterium shows how quickly the water in the body turns over. People with higher water turnover usually need to drink more water.

The report suggests that people living in hot and humid environments and at high altitudes, as well as athletes and pregnant and breastfeeding women, need more water because water turnover is higher among them. According to the study, men between the ages of 20 and 35 converted an average of 4.2 liters per day, while women between the ages of 20 and 40 turned over 3.3 liters.

Prof John Speakman from the University of Aberdeen toldBBC Radio’s Good Morning Scotlandthat the original estimate of two liters per day stems from a slight miscalculation. “The water we need to drink is the difference between the total water we need to take in and the amount we get from our food. The way they estimated the amount of food was by asking people how much they eat. Because people underreport how much they eat, there’s a misestimation and so you overestimate the amount of water needed,” he noted.

Mr. Speakman also clarifies that water turnover does not equate to drinking water needs.

He said: “Even if a man in his 20s has a water turnover of 4.2 liters per day, he does not need to drink 4.2 liters of water every day. About 15% of this value reflects surface water changes and water produced by metabolism. The actual required water intake is about 3.6 liters per day.Since most foods also contain water, a significant amount of water is brought in through eating alone.”