If you are particularly concerned about muscle you might consider adding vegetable juices. Drink fruits in the am, veggies pm. They are excellent for rebuilding. You can also add spirulina in either liquid or caps for extra protein.
I fasted 60 days, 45 on the MC, then fruits/vegs to day 60. I worked out every day barring crises, and didn't lose muscle. I did, however, lose hair for about 2 months after the fast due to metabolic changes (it grew back).