Lose muscle during MC?

I'm getting mixed opinions on this subject...

I've been thin all of my life. I'm 6'3" and 2 years ago I weighed 160 lbs. I've been lifting weights since then and have put on about 20 lbs. I'm concerned about losing muscle while on the cleanse. I do not want to lose muscle.

Some people have stated that I won't lose muscle while others say that as long as I do some light weight training, I will be telling my body that it needs it's muscle and to not use it as a protein source. A third person said that if I'm lifting weights, I'll be breaking down muscle and will need a source of protein to repair them.

What's the bottom line? Will I lose muscle? If so, is there a way to prevent that from happening?

Thanks