Comment by ravenstine

Men are also more likely to do strength training, which also helps build bone density. Women are also more likely to regularly perform cardio/aerobic exercises, which can reduce bone density when done in excess and without adequate nutrition. Lack of estrogen is of course the root, but I think we can't dismiss behavior differences contributing to the effect. In my experience, many women do minimal to no strength training because they're worried that muscle tone will make them look masculine. Maybe this is a really bad idea to live by.