You shouldn't really lose much muscle as long as you're resting as much as possible. Even still you will regain it very quickly, especially when you consider muscle memory.
10 Days is right when you get into a serious fast of real healing. From day 10 onward you're doing some deep cleaning. So you can do a short fast of 10-14 days which is recommended by Fuhrman for most people with NO chronic illness, but seeing as you mentioned hep, I would really recommend you to shoot for 21 days or more if you are able.
A 21 day fast will do exponentially more for your health than 10 days. I hate to use multipliers but it would be at LEAST 4x as much healing as a 10 day fast even though its only 2x as long. And then each day above 21 is going to be even more exponentially beneficial. A 35 day fast would be amazing and near the upper end of what is "required".