Eight glasses of water a day — it’s what we’ve always been told we need to drink to stay hydrated.
But how true is it? If we only get four glasses in, or six, are we in trouble?
Emily Oster at FiveThirtyEight tackled the question, and she started with where it came from.
Here’s what she found:
The best answer I can find (based on this review) is that the source was a 1945 publication by the National Food and Nutrition Board, a government advisory agency, that stated this: A suitable allowance of water for adults is 2.5 liters daily in most instances. … Most of this quantity is contained in prepared foods. The theory is that people read this, ignored the last sentence, and the eight glasses a day (about 2.5 liters) recommendation was born.
Myth busting site Snopes.com labeled the eight glass rule false.
In general, to remain healthy we need to take in enough water to replace the amount we lose daily through excretion, perspiration, and other bodily functions, but that amount can vary widely from person to person, based upon a variety of factors such as age, physical condition, activity level, and climate. The 8 glasses of water per day is a rule of thumb, not an absolute minimum, and not all of our water intake need come in the form of drinking water.
There is water in many of the things we eat– vegetables, fruit, meat and more.So here’s a new rule, via the Mayo Clinic: Drink enough so you aren’t thirsty.