Expert tip of the day: Start building bone mass early in your 20s to protect bone densityWhen it comes to preventing bone loss, timing matters. The best time to start protecting bone density is in your 20s. Why it mattersThe earlier you start building up your bone mass, the more bone you have to lose later on. How to get startedThe most effective way to build bone density is through a combination of specific exercises and nutrients, no matter your age. Some of the best foods to support bone density include cottage cheese, yogurt, milk, salmon and tofu.