Anthony Acierno Doctor's Corner, Nutrition Leave a Comment

Do we really need 8 glasses of water a day?

Question: “Do we really need eight glasses of water a day?”

Answer from Dr. Daniel Gruber, urogynecologist from Sibley Memorial Hospital in Washington D.C., part of John Hopkins medicine. 

This is an excellent question, with a lot of controversy surrounding it. You’ll hear lots of different things about how you should drink half of your body weight in ounces and other recommendations. But truthfully, the amount of water you need is very variable. It really depends on the person and on what you’re doing that day. 

For most people, unless you’re old, frail, and/or ill, your body will regulate its water just fine. You can be thirsty, and you drink. You get more thirsty, and you drink some more. It’s just like getting hungry. If you get hungry, you can eat more, but nobody would advocate for eating before you get hungry. So, it’s not a big deal for the vast majority of people to not drink that much until they get thirsty. 

If you’re in a situation that’s very hot or humid, and/or you’re working outside or exercising, then you’re definitely going to need more water. But then say if it’s winter time and you’re inside, and you’re not doing a whole lot so you’re not sweating that much, then you need less water. 

I’m biased because I see a lot of patients who over drink, in my opinion, and that causes a lot of bladder problems. They’re going to the bathroom every 30 minutes or 45 minutes and it’s very disrupting to their day and especially at night for sleep. 

So, it’s important to understand what works for you as far as hydration, noting that some people will use hydration as a diet technique to help them eat less. If that technique helps you, that’s wonderful. 

And there’s always a balance of what’s going to be the right amount, depending on your size. You know if somebody is very small, say 100 pounds, they’re going to require less water than somebody who is 250 pounds. And again, activity really matters. 

The whole notion of the ‘six to eight glasses a day,’ I had heard at one point, came out of an opinion article in the 1920’s. I haven’t been able to corroborate this, but that’s probably somewhat true. There’s just so much opinion around this question, and the reality is that the amount of water you need really depends on the person – there is no one easy answer.

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