n2bbuilding

I had a similar experience when I started weight training. I have always been a runner so I did not cut back when I started weight training.

Your cardio is cannabalizing your muscle tissue for energy. So you might try cutting your cardio down. but be aware that the problem that you are experiencing is pretty normal and you can't really avoid it if your goal is fat loss. It is pretty typical to lose some muscle mass when cutting.

Hope this helps.