We know the old adage well: Drink eight glasses of water every day to stay healthy and hydrated.
Doctors have given their patients that line for decades, but as it turns out, there may be no reason to obey their orders.
After reviewing clinical studies, health experts at the University of Pennsylvania found no evidence that the eight-glasses rule makes an already healthy person any healthier.
Pennsylvania medicine professor Stanley Goldfarb, who co-authored the review, has studied kidneys his whole career. He recently became interested in the way kidneys handle water.
In his research, Goldfarb considered the “eight glasses a day” rule and searched for its origin. He found no studies related to the rule.
Goldfarb hoped his study would remove the guilt some Americans feel when they miss their daily dose of water.
“People are forcing themselves to drink water all day, and they can be relieved of that,” Goldfarb said. “For a lot of people it’s a burden.”
Those who prefer sports drinks or juices over water can also breathe a sigh of relief: Any non-caffeinated liquid will hydrate the body just as effectively as water.
Especially among athletes, “if you just drink water, often you don’t feel as good,” said University Health Center Director Ben Douglas. “In addition to drinking water, it’s good to drink other stuff or eat.”
However, Douglas said, remember that sugary drinks sometimes contain hundreds of calories.
Goldfarb’s study may have eliminated the need for a strict “water regimen,” but that doesn’t mean people should quit liquid altogether. Water isn’t proven to clear away headaches or toxins, but it prevents kidney stones from developing.
So how much is enough?
“When you’re thirsty you should drink,” Goldfarb said. “That’s really the only rule.”
People who actually enjoy drinking eight glasses of water a day won’t harm themselves doing so, but there is such a thing as too much water.
“When you drink a lot of water in a very short time, it gets absorbed by your digestive tract quickly,” Douglas explained. Too much water absorption can then alter pH levels in the blood, causing lightheadedness, brain malfunction and even death.
As a general rule, drink when you’re thirsty, Douglas said, and stop when your stomach feels full.
“If you’re going by your thirst, then your body gives you good feedback about what you need,” Douglas said.
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