I got into yoga a few years back and lost a lot of weight. But not through just hatha yoga (or whichever type of yoga you may be going to try), but through the whole lifestyle. Eating wholesome foods and meditating are just a few other parts of a "yoga" lifestyle.
I lost about 10 pounds by spending 2 weeks at an ashram (went from 137/138 down to 129/130), where I basically lived a yoga-life and felt the best I've ever felt. Wholegrain foods, nothing processed at all, and daily meditations with one hour hatha yoga sessions- it was hard for the first few days but wow, when i got home and got on the scale I was amazed that I had lost weight without even trying or thinking about it.
That said, taking yoga classes or just trying yoga at home can only benefit you and help you lose weight. At least, it did for me.
Also, there are some awesome dvds/videos for doing a 20/30 minute "workout" in your home- I used to do this Yoga in the AM first thing in the morning and found it was so refreshing and it got my body moving for the day.