We're All For Staying Hydrated But How Much Water Should We Really Drink In A Day?

The famous ¡°8 x 8¡± rule where you are supposed to ideally drink eight glasses of water a day is not only supremely difficult to follow (ask anyone who has mustered the courage to drink more than 5 glasses of water everyday), it's actually unjustified.

In fact, nobody is sure where the idea came from and Science surely doesn't back it. The question then becomes: how much water should we really be drinking every day? Well, according to Science, your body knows best.

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The problem with the 'eight glasses a day' rule is that this estimate or generalisation can be a little off for people keeping in mind factors like different body sizes and types, varying body temperature and activity levels.

On days when a person isn¡¯t active, eight glasses of water could be an excess. Consuming water in excess leads to a lot of water being excreted. And with that one ends up flushing out vital nutrients like Sodium.

On the flip side, a person working out on a hot day could most likely end up consuming more glasses of water than the recommended eight.

We tried to understand how thirst is regulated and what drives it, and we came across a study conducted in 1990s on a group of people. According to the study, the mouth and stomach both send signals to the brain when we are full, and this means we don't need to drink more water. But the mechanism of how these signals reached the brain remained a mystery.

That was until three years ago when researcher Zachary Knight worked on understanding this very mechanism. He tried to understand how the stomach and mouth send signals to the brain telling it we are satiated. He did so by conducting experiments on mice.

But why mice? Because their thirst mechanism is similar to ours. When thirsty mice drank water, sensory signals raced to the brain¡¯s hypothalamus shutting down thirst neurons immediately, as reported in the journal Nature.

¡°This fast signal from the mouth and throat appears to track how much you drink and match that to what your body needs,¡± was the conclusion of this research. The brain rewards the drinking of water, but then there¡¯s a gut check.

Yet more research on mice found that gulping water ¡ª specifically the physical motion in the throat, which is different from the motion of swallowing food ¡ª also sends the same signals of being full to the brain¡¯s thirst neurons. This study by Caltech assistant professor of biology Yuki Oka and graduate student Vineet Augustine, was published in Nature last year.

"This is an absolutely new way to look at thirst, as we show that it is not just your brain but your throat and the gut that play an active role in quenching thirst much before your blood gets diluted by the ingested water,¡± Augustine verified.

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So how much water should you really drink? There can't be a hard, concrete rule. The key is to find a right balance. Even water needs to be consumed in moderation.

Drinking too much water can be deadly. A rare condition known as hyponatremia (a low level of sodium in the blood) that can be caused by drinking water in excess was the cause behind the deaths of 14 athletes, according to a 2015 report published in the Clinical Journal of Sport Medicine.The report issued this new advice to athletes: drink when you¡¯re thirsty.

The good news is, if you¡¯ve had enough water, your body will tell you. Research led by Farrell, the Monash University professor, found that when people drink plenty of water and don¡¯t feel thirsty, swallowing more water requires more effort ¡ª three times as much, people in the study said.

The key takeaway is to do what comes naturally. Drink when you want to, and chances are that you will be absolutely okay.