Just read through here and you will find that you will NOT lose muscle tissue, just some fluids - the fat will be attacked first. I weight train too and heavily and haven't found that I've lost any muscle mass, in fact it's increasing and I'm getting stronger and I took a week off not because of the Master-Cleanse but because I got a cold. I've also found my squats are better because an old knee injury for some reason, has suddenly stopped bothering me.
Remember each person is different and you're going to find that unless your hubby or others you know have done this fast to any degree (not a day or two), they can't really say what's happening or going to happen.
My Doctor (a real sports med doctor) put me on this because I'd gotten back into weight training and need to find my body beneath all this excess fat I've gained over the years, plus my BP is high and he says everybody needs to detox and often. After this, I'm doing the liver cleanse/flush too.
I can honestly say I've never felt better and another strange thing - before I started this I had a hard time walking more than a couple of miles on the treadmill and doing the stepper and now I just have so much energy and lasting power that I could go on for hours, without a problem.
So, that's my .02 worth, if it helps at all. Remember, you're doing the cleanse for you, nobody else.