I have tried 5 days once and started losing hair (I have thick hair as well). Not sure if it was something due to my genetic predisposition, but it is not a good idea for everyone. Maybe alongside some light physical exercise/walking, and water with the proper minerals etc. this could have been prevented.
I have read elsewhere, beyond 48 hours it is pointless and actually starts to be harmful, and you still get all of the benefits you mentioned above anyway.
There is also a lot of religious horse shit surrounding fasting in Hinduism/Buddhism so be careful about this as well. They promote this stuff for a reason.