Muscle gain/ weight loss

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So in attempt to avoid becoming "skinny fat" while I reach my GW I was doing a little research.

So I have a gym membership where I normally walk (3.0) on the treadmill at an incline for an hour a few times a week. It helps me break a sweat without actually "running". I also do nike fitness on xbox kinect 3 times a week for 40 minutes, and attend a yoga class at my gym.

Is yoga is a proper supplement for "strength training", because you are using your own body as weights?

Thank you :)