Will my German Shepherd puppy ever put on the weight to match his size?

I have a German Shepherd I got at about 10 months old. He supposably has Panosteitis, well thats fine and all but I'm curious will he ever put on the weight to match his size.

He has a huge front end and a little tiny back end...Kinda like a body builder that never works out his legs. He's a good dog hes just the size of a full size shepherd and underweight. Thanks!