Hey Julie,
It sounds like you are doing everything right. The weightloss can be frustrating I know. Are you close to your goal weight? I can't remember. Somtimes weight comes off very slow when you don't have much to lose. I used oxypowder before my fast. I think it pretty much liquifies everything in your system, so not sure you would see anything black. I never did when I did the bowel cleanse. Now with my enemas however, I see candida threads and possibly parasites, although I am not positive. There is definately unknown "stuff" coming out. My own past experience with liftinf weights wasn't good. My weight loss stopped for like 7 weeks. That was enough for me, I stuck with yoga and walking or light jogging. I know they say muscle weighs more than fat, blah blah blah, but when you have 40 pounds to lose, you don't want it all turned into muscle.
GOOD LUCK YOU WILL GET THERE...Hanna