I'll let Dr Carroll rant for me: https://www.youtube.com/watch?v=hbHp7cu2Ubk
I'll let Dr Carroll rant for me: https://www.youtube.com/watch?v=hbHp7cu2Ubk
This has recently been called into question as well, as the original study showing "ego depletion" failed replication.
3.2 liters of water (on top of all the water we already get from prepared foods, coffee, soda, etc) is still a _crazy_ amount of extra water.
I think the concern people have with coffee is that caffeine is a diuretic, so you lose more water than you take in. While it's technically true that coffee does make you urinate more, it's a very tiny effect.
Somehow the media managed to drop the last part, and recommended you drink at least 2l water a day. Or even more.
Source: http://www.sciencealert.com/there-s-no-evidence-we-need-to-d...
I know of no credible research that shows that drinking more than required to still thirst is beneficial in a healthy human.
One data point: my neighbors, husband and wife, are a surgeon and a neurologist. We live in the mountains of central Arizona, and hiking is a favorite pastime. Both of these doctors say one should drink 1 quart of water an hour while hiking. I don't quite do that, but I certainly drink 2 liters on a strenuous 3 hour hike.