So I am on like day 12 of being obsessed over new smartphone. It is my first one and it is an Android with the touch screen plus bells and whistles. It is freaking AWESOME. And than there are all the applications you can add, called app for short. Wow those are fun: there are games to play alone or with others, you can link up to you bank, check when the bus will past next, listen to music, etc.

Than I fell on the Drinking Water App. It asks you how many glasses you want to drink in a day, asks when you want to have your first drink (like 9 am) and the latest time to drink. When it is time to drink the phone makes a noise of a glass being filled. It’s a fun app for someone wanting to drink more water than they already are. If you achieve your daily goal a crowd applauds and cheers you. This is what the app screen looks like…

That got me thinking about articles I vaguely remembered reading some time ago: do you really need 8 glasses a day?, what is the size of a glass?, do your other beverages count and which?, and what about the water in the food we eat?

Oh gees, all I wanted was an app that may help me incorporate a healthier habit and inspire me to do more maybe? But now I am bombarded with existential questions about liquids. ENOUGH. Let’s get to the bottom of the glass and find the answers.

So according to wiki

The human body is made of between 55% to 78% water. Now how much you need per day depends on so many factors one cannot give a specific amount that fits every human being. Factors include on body size, level of activity, temperature, humidity. Some people may need one liter while another person needs  seven liters of water per day.

Who said 8 glasses a day?

We used to think that approximately 2 liters (6 to 7 glasses) of water daily was the minimum to maintain proper hydration. Where did this number come from? It goes back to 1945 when a recommendation for water intake was presented to the Food and Nutrition Board of the United States National Research Council. Since then many studies have been done to prove the claim, all have failed. In the US, the reference daily intake (RDI) for water is 3.7 liters per day (l/day) for human males older than 18, and 2.7 l/day for human females older than 18,  including water contained in food, beverages, and drinking water.

What does water do for you?

What is the size of a glass?

This one they all seem to agree on: eight fl oz each (240 ml).

What about the water in the food we eat?

Normally,about 20% of water intake comes from food, while the rest comes from drinking liquids. This means that with the current US recommendations, after eating you still need on average 3.0 liters (13 glasses) for a man and 2.2 liters for a woman  (9 glasses). Wait a minute that is even more then the old false recommendation of 8 glasses? Now I am really confused.


So how much do we really need per day?

Medical literature favors a lower consumption, an average sized adult with healthy kidneys needs no more than one liter of fluid (4 glasses). Another article I read recommended 1 liter of water for every 1000kcal you expend. If it is hot and humid, drink more, if you exercised drink more. If you sit all day and no nothing in a cool comfortable room there is no need to add more.

The “loose average” kcal burned in a day is 1800 ( an average people…some are at 1400, some are a 2200). So let’s take off 20% because that water was in our food. Now we have 1440 kcal which would be 1.4 liters or 6 glasses.

This is another formula (apparently) to learn what your liquid daily needs are:
To determine how much water you should drink, weigh yourself each morning for 3 to 4 days in a row (ladies not during your PMS or period cause you are bloated). If you lose a whole pound in a day, it means you came up short on liquids the day before. Drink a pint of water or juice first thing in the morning for every pound you’ve lost and adjust your daily intake until your weight is steady.

Do other beverages count?

Water is water is water? Actually no, beverages such as milk and juice are composed mostly of water. Same goes for beer, wine and caffeinated beverages. Of course I won’t recommend you only drink beer, but if you have a glass of milk in the morning, a coffee at work and a beer at night…if you are that average 1800 kcal person you just knocked off 3 of your 6 glasses.

In the end I decided to set my Drinking Water app to 6 glasses and I count all my liquids as water. So far so good.

A final note

I read a couple of sites that said you are your best judge of how much water you need to drink. I actually totally disagree with that because most of us misinterpret “I am thirsty” brain signals as “I need to eat something”. Yes most of your pangs of hunger are actually your body saying it needs fluids, not food. When you are really hungry you will know it – like you might want to steal the sandwich from that kid and run because you are starving.

Also some people only recognize thirst when they are already dehydrated. If that is your case better drink by prevention before you feel thirsty. Dehydration can be life threatening.

And yes you can die from drinking too much water too, although that is rare. It is referred to as water intoxication or hyper-hydration. If you drink so much water that your normal balance of electrolytes go out of wack your muscles and brain will stop functioning. Nearly all deaths related to water intoxication in normal individuals have resulted either from water drinking contests.