Hi holspen, welcome and thanks for your question.  Since you are going to a gym have you asked what type of exercise is best for this area?  I know how hard it is to get rid of the extra weight we carry around the stomach.  Your Dr. should be able to recommend some specific exercises as well.

I don't know if you have any medical problems that would limit your exercise, but if you do, you could get an appointment with a physical therapist, so they could evaluate your osteoporosis and give you an individual plan of exercises to do that would work on this area, without causing any injury to you spine or lower back.

Crunches and forward bending (like toe touching) is not a good idea, so get some advice from a professional on this so you don't cause any injuries, or fractures. 

Good luck, I hope you can find some exercises that are *specifically* designed for you that are safe with osteoporosis.