who established water amount of 64oz? that seems high to me!

[bfa]

64 oz of water seems difficult to obtain.  Should I just adjust downward since I also drink a lot of coffee and tea?

[gerrymcd]

I agree completely.  There is a bit of an issue relying on urine color as a metric of your hydration. Most people motivated to try and drink 8 x 8oz glasses of water a day (over and above the water in food, tea, coffee, etc) are almost certain to be taking vitamin supplements.......which often colour urine darkish yellow or orange.  

[Jackinga]

How about a loggable scale for various things related to hydration then?

For example, have a graph that shows data points logged by the user. 

On a scale of 0-4, level of thirst vs time where one specifies the time and thirst level:  0 - not thirsty at all; 1 - not conscious of thirst, but drank something anyway; 2 - thirsty: 3 - very thirsty; 4 - parched feeling, thinking only of a drink.

Time and relative color of urine: 1 - normal, light colored; 2 - darker than normal; and 3 - very dark.  These things could be plotted together on a hydration scale along with amount of liquid in oz consumed at a given time.

Since the urine color scale as given is achromatic and relative to a given individual, diet and supplements could be readily allowed for.  For example, I am fond of cooked beets, some of the color of which is definitely passed through my kidneys.  My vitamin and other supplements including lutein and xanthine do not normally affect my color.   Thus the above scale is meant to be more relative to Beer's law than to a given spectral absorbance.

And, yes, there is such a thing as Beer's law or the Beer-Lambert law, sometimes called the Lambert-Beer law, which can be stated as absorbance = e b c; where e is the molar extinction coefficient; b is the path length through which the liquid is viewed; and c is the concentration of the solution.  Assuming e = 1 and b =1 (or are at least relatively constant for an individual) then a = c.  And it is c, we would be estimating on our dimensionless, relative scale.

[Docwyoming]

"

The whole of it is that eight 8 oz glasses of water a day is pure nonsense. 

Fitbit should drop this from both the dashboard and the log as it (in its unqualified form) casts grave doubt on the veracity of other Fitbit features by its presence."

This is what I came here to say. The snopes article debunks this pretty well. The link someone gave to the May clinic actually REFUTED this claim and went against what the poster was trying to argue. 

Fitbit looks BAD for keeping this bit of antiquated nonsense on the site. 

[gerrymcd]

Yes, in principle that would work, except, its not really feasible to assume e is 1 given the influence of food (vitamin supplements for example) that change the molecular composition of the urine (and hence change e dramatically).   Its the great First World cycle, people take supplements - which color their urine - which makes them think they need to drink more so they produce a crystal clear stream!

[Ryboflavin]

To be honest I don't think the 64 oz is a hard fast rule. It was likely established by the FDA after some study that focused on a single factor. Looks like the other responders have posted some good links.  

That being said its important to ensure you are getting enough water to replace sweat and other excretions. I believe water consumption aids the kidneys and liver. These organs filter out waster, minerals, and other things from your blood.  Water helps flush those organs.  No kidney stones for this guy.

That being said coffee and tea are diuretic, which promote the body to produce urine and excrement.  Be sure you are drinking enough liquid to replace what you excrete.  

Personal I drink about a gallon of water a day.  Its a habit I'm in to help keep me feeling full and helps to teach my body not to store water, so less bulk. The issue with drink too much water is that you need to replace the electrolytes. I sometimes add potassium, salt, lime juice, and magnesium to my water to supplement. Particularly if I'm engaging in an activity that causes me to sweat a bunch, like hockey, surfing, or a lot of running.

[Ryboflavin]

@Jackinga I'm not disagreeing with you regarding the 8x8 rule. Its a bit arbitrary. However, I do like the liquid consumption metric.  I use it to ensure I'm not fluctuating too much day to day.  

It could be useful to a dietitian or a doctor to understand issues surrounding chronic dehydration, headaches, kidney stones, etc.

[matt9013]

I lowered mine to 33.8 oz. I drink a lot of water but I could never get to that amount. I only added water I knew 100% I had drinken so I wouldn't add some sips here and there so maybe I did get 64oz but it's hard to track unless you know the correct amount like from a water bottle.