Question about tongue coating and breaking fast

Hi all. I am on day 4 of my fast. I am wondering how many people on here have actually fasted to the point where their tongue turns back to a healthy pink color.
I haven't found any proof that white tongue is caused by detoxification but i have found multiple scientific sources stating that it is due to vitamin deficiency. So i am asking here if anyone has successfully fasted to the point where their tongue goes back to normal or does it stay white the whole time for you??
I ask because i am trying to think of a goal for how long to fast but i have read on here that and a few other web pages that you need to wait until tongue isn't white anymore but i am having some doubts about the validity of that concept.
Thanks