Science how much water to drink

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I am an exercise physiologist , and my research focuses on overhydration and how drinking too much water affects the body. Since water — and sodium — balance is essential to life, it is extremely rare for people to die from drinking too much — or too little — fluid. As spring unfolds, hydration challenges take root across schools , sports and workplaces. These heavily marketed hydration challenges serve to cultivate both camaraderie and friendly competition to ensure that we drink compulsory amounts of water throughout the day.

But this is not so. Individual body water needs — intake — are primarily based upon how much water people lose. How much water each person needs to drink mainly depends on three factors:. Perhaps, this two-liter intake threshold is derived from a misinterpretation of original recommendations offered by the U.

Food and Nutrition Board in as well as the European Food Safety Authority, which states the daily recommended amount of water includes all beverages plus the moisture contained in foods. As many countries urge populations to stay at home, many of us are paying more attention to our diets and how the food we eat can support our health.

To help sort out the fact from the fiction, BBC Future is updating some of our most popular nutrition stories from our archive. Our colleagues at BBC Good Food are focusing on practical solutions for ingredient swaps, nutritious storecupboard recipes and all aspects of cooking and eating during lockdown. In the early 19th Century, people had to be close to death before deigning to drink water. Many people, he added, had never drunk more than half a pint of plain water in one sitting.

How times have changed. Adults in the UK today are consuming more water now than in recent years, while in the US, sales of bottled water recently surpassed sales of soda. Commuters are encouraged to take bottles of water onto the London Underground, school pupils are advised to bring water into their lessons and few office meetings can commence without a giant jug of water sitting in the middle of the desk.

Many of us believe we should drink at least eight glasses of water a day Credit: Getty. To add to the confusion, as the current pandemic took hold people were advised to tap a sip of warm water every 15 minutes to protect against the virus — advice that has no basis in fact.

Why is there so much unclear information about how much water to drink? Most likely, it seems, from misinterpretations of two pieces of guidance — both from decades ago. In the US Food and Nutrition Board of the National Research Council advised adults to consume one millilitre of liquid for every recommended calorie of food, which equates to two litres for women on a 2,calorie diet and two-and-a-half for men eating 2, calories.

In the original guidance, your daily allotment of liquids could include fruits and vegetables Credit: Getty. In , meanwhile, the book Nutrition for Good Health, co-authored by nutritionists Margaret McWilliams and Frederick Stare, recommended that the average adult consumes between six to eight glasses of water a day.

But, the authors wrote, this can include fruit and veg, caffeinated and soft drinks, even beer. Excessive water intake can be dangerous, particularly in those with heart conditions. View author profile. We do get a lot of our water intake from the foods we consume.

A one-size fits all approach is unlikely to be helpful. Healthy adults may not need to drink an additional eight glasses of water a day. On the other hand, persons with certain diseases or living in very hot climates may require larger intakes of fluid. Eight glasses, which is just less than two liters of water, is very roughly the basal water required by a fasting, well adult per day, who is doing nothing at all for example, staying in hospital , with no special losses such as vomiting or diarrhea.