How much water we need to drink every day?

You know those ads that remind us that even a small reduction in levels of hydration tremendous impact on performance , so you need to keep hydrated with whatever brand of super isotonic drink that they sell ?
They seem quite scientific. Are they for real? A man in a white coat , an athlete with electrodes attached and so on . And it is not hard sell because drinking feels right - you're hot and sweating , no doubt where the fluid must be beneficial .

Well earlier this year sports scientists in Australia made a remarkable experiment has never been done before ( British Journal of Sports Medicine , September 2013 , current hydration guidelines are wrong : Not dehydration impairs exercise performance in the heat , Wall BA ) .

The group is keen to find out what happened to the performance after dehydration . So , they took a group of riders and exercised until they lost 3 % of their total body weight in sweat .

Their performance was then assessed after rehydration with either 1 ) no , 2 ) sufficient water to bring them back to 2 or 3 % dehydration ) after full rehydration .

So far nothing unusual , but the difference between this and almost every other study that has ever been done on hydration was that the riders are oblivious to how much water they get . Was given IV fluids without knowing the volume.

This is essential because we all , and especially athletes , have such a close relationship with psychological water consumption .

Remarkably , there was no difference in performance between those who fully rehydrated and non world . This study is part of a growing movement to " drink to thirst " hoping to persuade athletes not to over hydrate and consequently potentially deadly level of diluting your sodium , causing hyponatraemia .

We can tolerate losses in water relatively good , but even a little over hydration is far more dangerous".

Perhaps it should be so surprising outcome . Humans evolved intense exercise in the heat and extreme drought . But what about the rest of us who do not cycle around the desert in Western Australia ?

It is very well accepted idea that we should drink about eight cups of water a day ( 2-3 liters ) in addition to our food and other beverages . We are awash with positive messages about the healing properties of water and how it will improve everything from our brains to our intestines . And we know that without it I would be dead in days .

It is a short step from logic to think if water deficits are bad for you , hydration must be good - we need purification , clean water washing through your organs may be beneficial , detoxification . It certainly improve your skin, help you think , will reduce your risk of kidney stones and turns your urine pale , straw / champagne color lovely orange syrup instead fetid you produce at the end of a long day where you have not had time to drink.

So I have looked through the literature and I found a review article says all this and more. It was written by a highly respected group of doctors from hospitals America and France , and it clearly supports the common belief that you should drink 2-3 liters of water a day .

He says that people with high urine output is a lower rate of kidney stone disease , the flushing action of the water can reduce the risk of urinary tract infection (particularly in women after sex ) . Perhaps most importantly , they point to a study that showed surprising that paradoxically drinking water increases the risk of bladder cancer . But only tap water . And the idea .

A footnote at the end of the article explained that what you thought was a scientific article in a scientific journal is actually a supplement , sponsored by the large mineral water manufacturer . All of the authors received honoraria from this company , which also provides medical writing assistance . So , this is not research , it's marketing .

We are constantly told to drink more water : it clears skin , reduces fatigue and focusing aids , but drinking too much water could be dangerous ?

And this is one of the reasons why we are even discussing this - because there was a growing drinking water is just coming out of our taps is free. It sold to us by the same people who sold us clever yogurt with bacteria in them that probably makes us much good , something I look at separately in the TV series I've been doing . And these companies are fairly consistent recommend 2-3 liters of water a day .

So , where did that number come from and is there any reason to think it correct ?

Well, there's a grain of truth in this - people in temperate climates do not exercise continuing need about six to eight cups a day , but can be included in food , alcohol or caffeinated drinks .

But the big thing is that you need to worry about exactly what that requirement daily total just as top-level athlete because your body will sort it all out for you.

If you drink too much you pee out . If you drink enough you get thirsty and pee less . All this exquisitely well - managed in the same way that the amount of oxygen in your well - control .
Saying that you should drink more water than your body is asking for is like saying that you should be aware breathing more often than you feel like a bit of oxygen because if you are good , then more must be better .