Throwing cold water on popular theories

Mar 9, 2014

Water, water, everywhere. At least, that's what we've been told.

Health, nutrition, exercise and beauty experts of all kinds have said over the years that we need to consume a certain amount of water per day, that we need to drink water before and after exercise, that drinking lots of water can help you lose weight, that drinking lots of water helps the skin, and the list goes on and on.

But what’s the science behind all these claims?

Click 'Read More' to hear our interview with Dr. Goldfarb.

This week on “Take Care,” Dr. Stanley Goldfarb, professor of medicine at the Perelman School of Medicine at the University of Pennsylvania, with a specialty in renal electrolyte and hypertension, separates fact from fiction about the benefits of water.

“Water is crucial to health, it’s crucial to life,” says Dr. Goldfarb.

Anywhere between 50 to 70 percent of the human body is composed of water, so it’s no wonder that people cannot survive without consuming water.

Because of that, Dr. Goldfarb says that the body has multiple systems designed to make sure it maintains a very constant level of water content. But, if you drink extra water, the body is designed to excrete it.

“Any water that’s ingested doesn’t stay in one particular compartment, but distributes itself throughout the body and then is rapidly excreted until the amount of water in the body returns to the baseline,” said Goldfarb.

So how much water does a person need to consume each day? Dr. Goldfarb says there is no set amount you need to drink for optimum health, but rather the body needs to replace whatever amount of water it loses through the skin and the urine -- which, according to Dr. Goldfarb, is usually around one and-a-half or two quarts a day.

“As long as you equal that, you’re going to stay in water balance and have absolutely no consequences to your health.”

So what about the claims of some exercise experts that if you allow yourself to get thirsty, you’ve waited too long. Dr. Goldfarb says no. As long as you drink when thirst occurs, you’re going to make up the water that your body has lost.

And, according to Dr. Goldfarb, consuming water before exercise does not improve performance, something which has been tested on elite athletes.

“This idea that you have to carry around water bottles during exercise, there’s no real evidence that’s going to improve exercise capacity or prevent you from having medical problems or make you healthy in any way anyone can measure,” says Dr. Goldfarb.

Now, getting dehydrated is a health risk. Goldfarb says when you are thirsty, it probably means your body has lost one, or perhaps two percent of its water content.

But if a person avoids water when he or she continues to be thirsty in a hot environment and/or exercising, the body can lose over five percent of its waterand that’s a dangerous situation. At 10 percent loss of total body water, you can get dehydrated and risk death. But, Dr. Goldfarb says, anyone who feels a bit thirsty is at no risk of those complications

There is one kind of person who should drink extra water above and beyond what their body loses each day – someone with a history of kidney stones.

“That’s the one area that’s drinking lots of water and keeping your urine quite dilute has been shown to prevent recurrence of kidney stones.”

Besides that, Dr. Goldfarb says there is no evidence that drinking lots of water:

Bottom line: drink when you’re thirsty.

“The question has been whether… making sure you drink, not only in addition to the amount that you are required to by thirst and by obligate water losses, drinking above and beyond that is going to produce any health benefits. And that’s where it’s quite clear there’s just no evidence to support that.”

Next week, "Take Care" has part two of our interview with Dr. Stanley Goldfarb on water and the body.