I have found/learned (thanks to some folks here:)to take it easier on the fast and let your body use that energy to rebuild. As far as loosing, merely walking burns 500 calories per hour. If you are only taking in 1000 calories on the Master-Cleanse that's 50% of your intake. I limit my exercise to walking an hour a day and heavy stretching...once a day I do a few reps of something ... Although I used to ,while on the Master-Cleanse work out and run just as hard and as long as normal...lots of energy!!!
You can eat away muscle if you work out hard...I quit doing that...you can actually eat away at your heart muscle,too!