Hi,on a water fast muscle loss is minimal when the body is in full ketosis mode. I do feel light and I notice my clothes are not tight anymore. I feel like I have lost more inches than weight. When water fasting you do lose weight and less muscle is lost because the body conserves vital tissues and organs. When I started the fast I thought I won't reach even day 7 but I took it a day at a time. Usually after 3-4 days you stop feeling hungry. So stay strong and you will reach your goal. Good luck on you fast.