DEXA scans are the gold standard for figuring bone density. If you’re trying to figure your PBF or LBM, or even a objective measurement of your BMR, what you want is a scale that utilizes BIA technology. Inbody makes the really good scales with multiple points or contact and different currents. A lot of big gyms have these (newer models can reach like $20,000…) and you can pay some arbitrary amount of money to have someone put you on and take your measurement. If you’re trying to gain LBM, this is really important so you can actually see what’s going on behind the scenes. Also, you cannot spot lose, so if you do make some better habits into a sustainable lifestyle change where you see weight loss and muscle gain as the side effect, then you’ll eventually see the fat mass in your face decrease.
Yes, they are.
Body fat, muscle mass and bone density are crucial to longevity and living a high quality life (explained here).
Getting a scan done helps quantify where you now and track improvements over time.