Buzz
Written by Chris Gayomali
We've all heard that staying hydrated means drinking eight glasses of water each day. This equates to about two liters, which is quite a lot when you consider that the average human stomach (in its natural state) is roughly the size of a clenched fist.
However, health experts have dismissed the eight-glasses-a-day theory as a baseless myth, fueled by weak scientific studies. Moreover, many of the organizations advocating for excessive hydration have been found to have — surprise! — financial stakes in the beverage industry.
For instance, in a 2011 article published in the British Medical Journal, Margaret McCartney exposed the eight glasses-a-day myth, pointing out that the European water advocacy group Hydration for Health is not only funded by but was also founded by the food conglomerate Danone. Under its vast portfolio, you'll find bottled waters like Volvic, Evian, and Badoit.
If you look beyond the vested interests of Big Bottled Water, it's clear that numerous studies have shown how incredibly adaptable the human body is when it comes to hydration. For example, Saharan nomads are able to survive on minimal water for days in one of the harshest environments on Earth, as anthropologist Claude Paque first highlighted in 1976.
Meanwhile, most of us might feel a bit irritable if we skip a trip to the water cooler in our climate-controlled offices, but it's exceedingly rare that we'd suffer extreme dehydration to the point of danger. Consider everything else we consume. Despite the popular belief that tea and coffee dry us out, they actually contribute to our hydration, according to Dr. Stanley Goldfarb, a nephrologist at the University of Pennsylvania. Despite the common advice to drink eight glasses of water a day, "there's no evidence that benefits health in any real way and it really represents an urban myth," says Goldfarb. Even foods like a baked potato are 75 percent water.
So where did this eight-glasses-a-day belief originate? The concept of a "minimum water requirement" is a relatively new idea, first introduced in dietary guidelines in 1945 by the Food and Nutrition Board of the National Academy of Sciences. The board suggested that "2,500 mL [2.5 liters] of fluid should be consumed daily," though no primary clinical study was cited to support it.
This idea might have been partially promoted by Frederick J. Stare, a prominent 20th-century nutritionist and founding chair of the Department of Nutrition at the Harvard School of Public Health. (He passed away in 2002 at the age of 91.) Stare was one of the first to recommend that people drink six 12-ounce glasses of water each day.
Since then, experts have begun to recognize that eight glasses a day is likely an overestimate, particularly given our dietary habits. However, there are still advocates who push for the intake of eight glasses or more of pure water. Among them is Dr. Fereydoon Batmanghelidj, a Virginia-based medical professional who believes that a lack of water causes many preventable illnesses. After all, water is still beneficial. Recent studies suggest that proper hydration might not only boost cognitive function but also play a significant role in preventing chronic kidney disease.
As for how much water we should drink, unfortunately, there is no clear-cut answer. (Sorry!) When you factor in all the other fluids and foods we consume throughout the day, we actually exceed the recommended two liters. A 1995 survey conducted in Australia revealed that the average adult's diet provides more than enough fluid: Women, on average, take in about 2.8 liters per day, while men consume around 3.4 liters daily.
Research shows that drinking water when you start feeling thirsty is generally enough to keep you going. Of course, this varies depending on your activity level—whether you're drenched in sweat after spin class or comfortably spinning in your office chair. As with most things, it's probably best to listen to your body and respond accordingly.
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