Thanks to the ever-improving world of fitness trackers and apps, you've never had more access to personal health data. But which of the dizzying number of markers and metrics should you really be ...

For bodybuilders and fitness enthusiasts, changing body composition often reflects hard work and discipline—but knowing body composition is useful for anyone, and for more than just bragging rights.

A body composition test measures percentages of fat, bone, and muscle in the body. It can provide a snapshot of your overall health, inform strategies to improve health, and help gauge progress toward ...