How to deal with Osteoporosis

I have a friend of mine who is only 33 and told me he had his bone density checked when he complained that his knees are hurting whenever he sits or bends. He said his result of the bone density reading was a -3.0 - a sign he has osteoporosis.

Obviously, I told him to work out more since he could use some pounds to shed, and the common things to do like drink milk and avoid too much fats and stuff. But he doesn't want to take any medication to restore his bone health (neither do I). So I was wondering if anyone here has anything to add to help restore his bone density, particularly through diet and/or alternative treatments he can do. Thanks in advance. Tweet