The paper below explains the action of K2-MK7. Natto is extremely rich in K2-MK7. I can't evaluate the accuracy of the paper as I'm not a scientist but it could be useful information if trying the exercise and nutrition route.
"This large and statistically rigorous meta-analysis concluded that high vitamin K2 levels were associated with reduced vertebral fractures by approximately 60%, hip fractures by 77% and all non-vertebral fractures by approximately 81%. Supplementation with vitamin K2 as MK-7 increased bone strength in postmenopausal women in 3-year clinical study’."