A lot of people here do fat fasting, myself included! Sometimes I have black coffee but much of the time during the fast I will include HWC. There are discussions about what it does to autophagy and insulin spiking but I would say, go for it! Some fasting is better than no fasting. If you want to be pure, starting off with HWC and weaning yourself off over time, may get you there. I am not the purist type so I make do!
I did a 7 day fat fast last year. You can read it here: 7 day fast with daily numerical posts & 1 week post fast update
Also you can join us here as we will be using a variety of fasting techniques over the next few months: