In regards to cleansing. There is a reason why I recommend a two week cleanse (or longer if possible) Guys have kind of just taken it upon themselves to do shorter versions of this...intermittent fasting, two or three day cleanses, etc. This isn't enough. Sometimes it takes two or three days just for your body to really get into the cleansing phase and if you stop around that time, you've done nothing but dump a bunch of garbage into your blood stream that your body now has to deal with on top of your other symptoms. You basically stop it right as it's getting prepped to do what it needs to do.
Juice feasts are a little more forgiving because you're stll providing your body with nutrients and energy but still.....two weeks should be the minimum to shoot for....not less.
And yes, you will lose muscle and size, but you need to build a strong foundation before worrying about your aesthetics. Can't build a strong house with a foundation of mud. You need to tear down, and rebuild.