As soon as you have done your break by the book, start adding clean proteins like fresh fish and chicken breast.
I fasted 60 days two years ago and never lost any muscle. I worked out the whole time, barring detox crises, and was certainly weaker than normal, but that is to be expected while fasting. It does not necessarily indicate loss of muscle.
For a workout boost, try 1 tablespoon BLACKSTRAP molasses prior to working out. I like to dissolve mine in a cup of hot water and drink like tea. It really picks you up for the workout, and is part of the Master-Cleanse protocol.