Originally Posted by Bovice
Pretty much what Shinobi said
Only thing I'd add is that you can't target fat in any specific area; no one exercise will help reduce stomach fat than any other.
This is not necessarily true, buy choosing exercises that focus on the lower back and core muscles you can build muscle there which will in turn reduce the ammount of fat in in your stomach. As a competitive athelete who had been training for a very long time I can say this with confidence. If stomach fat is what your trying to loose it might be kind of hard with an injured back considering the core muscles and the mustcles in your lower back work together so much when you perform core exercises. I would say talk to a physical trainer, most gyms will let you consult for free or give you a discount on your first visit. They willl help you find exercises to tone the muscles you want without the high impact that will cause you pain (that's their job after all).