[rrosenberry]

I would switch to the food she LOVES, so she will eat again. 5 pound is not too heavy, if 2-3 pounds lighter you are feeling and seeing her ribs. Sounds like the right size for her, which very well could be.
I would suggest a vet also.. then try to find a better quality food that she will eat, they can be very picky. ( which it sounds like she is)
the Ol' sayin " If they get hungry enough they will eat" Just isn't true, I once switched foods, and my cat lost 4 pounds and would have starved rather than eat the new food.