""" The subjects' feelings of hunger and fatigue increased with the length of the fast—contradicting the argument often heard that hunger fades with prolonged fasting. Most discouraging, though, was that the fasters lost mostly muscle, not fat."""
Based on this statement it is clear that the fasts weren't done properly.
Its sounds like they were not sticking to the water only rule.
To lose muscle during a Water Fast you half to be adding something beside water to put the body into a starvation diet which is what has happened here.
For a successful Water Fast it is important to have water only.