I have severe asthma and can't exercise and I'm stilling loosing fine. It may take you a little longer, but you will get there. On another site there was a similar question and there is a video for chair aerobics so you might want to look into some exercising that doesn't hurt you back. No one wants that!
I used to weigh 356 pounds and I now weigh 169.2 so you can see I did lose.
