I'm new here and thought I would post a comment about yoga.
I take yoga three times a week. What kind it is -- I don't know. I take the yoga for the strengthening and toning of my muscles. This could never be the only exercise I do because I don't find it aerobic, but then I don't consider walking exercise either.
Let me qualify that, I didn't think of walking as exercise. Now I do. I go to 2 stretch and toning classes, one aerobic class, walk 4 days a week, and two sessions of nautilus and free weights training in addition to 3 yoga sessions every week.
I do get a little warm in my yoga classes because I am expending energy holding the positions, but I don't confuse that with aerobic activity. Yoga, stretching and toning, and using weights (resistance training) are probably considered anaerobic exercises and we need to incorporate both, the aerobic and anaerobic, in our exercise program. The resistance training is good because it helps the build muscle which will help your metabolism and that means burning fat.
So if you do yoga, good for you. But you will probably need to add some aerobic exercises to your program too. I enjoy yoga immensely, especially when I go right before work.