8 glasses of water a day and other myths - Cape Cod Healthcare

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Published on July 20, 2021

8 glasses of water a day and other myths

8 Glasses Water

Along with the warm summer weather comes the perennial discussion of how much water we need to drink every day. Is it really eight glasses of eight ounces each? For the answer, we went to an expert who knows all about the kidneys, the organ that has a lot to do with the regulation of liquids in our body.

“Everybody does have a lot of preconceived notions about how much fluid you should drink,” said Melanie Greenan, MD, a nephrologist who practices in Yarmouthport, MA and at FMC Mashpee Dialysis in Mashpee. “You need to use your sense and listen to your body.”

Thirst is an adequate indication that you need to drink something, which is contrary to a commonly-held belief that you should drink even before you are thirsty, she said. Many of her elderly patients often ask her whether they are drinking enough during the day, and family members who come with them are often particularly concerned.

“It’s usually the daughter saying, ‘can you tell her or him that he needs to drink more water?’ and I say, ‘no, I’m sorry because I can’t do that,’” she said. “ I can have the same conversation with the same family multiple times.”

As long as the person is drinking when they’re thirsty and drinking their usual beverages during the day, they are getting enough hydration, Dr. Greenan said.

In fact, most of her patients are overhydrated, which means they have too much fluid in the body, resulting in higher blood pressure and swollen ankles, she said.

It is true that the body’s thirst mechanism in the elderly isn’t as refined as it once was, but Dr. Greenan said she has only met a few people in her 16 years of practice who really didn’t drink enough during the day.

“The hormone balance can be a bit off as people get older, and we tell then, ‘don’t drink when you feel you’re supposed to; drink when you feel thirsty,’” she said.

Do Coffee and Tea Count?

Chances are, if you are drinking with meals (more often if you are perspiring) and eating fruits and vegetables during the day, you are getting all the hydration you need, Dr. Greenan said. Coffee and tea during a meal are fine and can give you the fluids you need, she said, disputing another common belief that caffeinated beverages can actually strip your body of fluids.

“I always tell people, ‘it’s a mild diuretic at most and a mild diuretic does not counteract the fluid intake,’” she said.

All fluids are the same when it comes to providing you with the hydration you need, she explained. But that being said, Dr. Greenan is a big fan of water as a source of fluids.

“My standard is that water is a good choice of a beverage. It doesn’t have any added sodium; it doesn’t have any caffeine for people who need to limit their caffeine; it doesn’t have any calories. But, it’s fine to drink another beverage,” she said.

As for alcoholic beverages, they are mildly diuretic, but actually do count towards your daily fluid intake. However, Dr. Greenan said she does not recommend that they be consumed in excess due to its harmful effects on the liver.

How to Tell if You’re Getting Enough

Those who do need to add extra liquids to their daily intake are people who lose more fluids than normal throughout the day, she said. We lose fluids in several ways, such as when we sweat from exertion or exercise, or some people have more active sweat glands than others. Loose bowels will also cause the body to lose fluids, she added.

So, how can we tell if we’re getting enough hydration?

“I like to tell people to kind of use your urine as a judge. So, if you’re peeing and it’s more on the clear side, rather than apple juice color, then you’re getting enough fluids,” Dr. Greenan said.

Becoming dehydrated can take a while and there are a variety of symptoms, depending how far along in the process you are.

“If you don’t listen to your body’s thirst signals, or if you’re in a situation where you can’t get enough fluids, or if you’re losing fluids rapidly, like running a marathon or working in the garden and forgetting to drink, you can get head-achy and generally feel kind of crummy,” she said. By the time you become dizzy or disoriented, you are far along in the process and should seek medical help, she added.

Although most of us obtain the amount of fluids we need through our daily drinking habits, drinking more is generally fine for people, Dr. Greenan said.

“There are definitely people who feel better when they have more fluids in them, and if you feel better, then that’s fine,” she said. “There are a few people that actually need to limit their fluid intake, but unless you’ve been told to limit your fluids, then it’s fine to drink as much as you want.”

Busting another myth about drinking lots of water, Dr. Greenan said it is scientifically not true that your skin will glow if you guzzle more liquids.

“A lot of people feel that it works for them and that’s fine and I’m not going to argue with them. But your skin doesn’t actually reflect your hydration status,” she said.

Overall, Dr. Greenan said the issue of how much water to drink shouldn’t be at the top of your list of priorities.

“I don’t want people to spend too much time worrying about their fluids,” she said. “ There are other things in the world to worry about besides how many cups of water you’re drinking.”