Experts say drinking eight glasses of water a day is actually too much

We all know that drinking eight glasses of water a day is the supposed holy grail of health, but it turns out that this might not be the case as a recent study has found it's likely too much for most people. Yep, we were gagged too!

According to the NHS—and other health and nutrition bodies like the European Food Safety Authority—we should drink six to eight cups or glasses (around two litres) of fluid a day, in order to flush out toxins and maintain healthy kidneys.

However, scientists from the University of Roehampton London have recently conducted "the biggest study of its kind" with more than 5,600 participants between the ages of eight and 96 from 23 different countries. The study could throw doubt on the whole eight-glasses-of-water-a-day recommendation, given that experts found the "one size fits all" policy for water intake does not work for everyone depending on a number of factors, including age, sex, location, occupation and more.

Many participants—for example, those living in hot and humid environments or at high altitudes, as well as athletes and pregnant/breastfeeding women—needed more water, as the research showed water turnover (the replacement of body water that is lost in a given period of time) is higher among them.

As for the biggest factor in water turnover, it's all to do with energy expenditure, explains the study's scientists. Men aged 20-35 turned over an average of 4.2 litres per day, which decreased with age, averaging 2.5 litres per day for men in their 90s. Meanwhile, women aged 20-40 averaged a turnover of 3.3 litres, which also declined to 2.5 litres by the age of 90.

But, water turnover is not equal to the requirement for drinking water, says Professor John Speakman. "Even if a male in his 20s has a water turnover of on average of 4.2 litres per day, he does not need to drink 4.2 litres of water each day," the University of Aberdeen professor explained. "About 15 per cent of this value reflects surface water exchange and water produced from metabolism."

Overall, the study found that the average male from the US or Europe should only be drinking between 1.5 to 1.8 litres of water per day after water intake from food is taken into account, while women should only have 1.3 to 1.4 litres.

"Water is essential for human survival and measuring our exact water requirements continues to remain a challenge," adds Professor Lewis Halsey from the University of Roehampton London. "This research sheds light as to how factors including climate, age, physical activity, pregnancy and water intake of food can determine how much water intake we actually need."

He goes on: "It is an important finding that can help create global public health policies regarding the provision of drinking water and water-rich food as concerns surrounding climate change, clean drinking water and global water security continue to grow around the world."

This article is not intended to be a substitute for professional medical advice or diagnosis. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.