How do modern weight measuring scales measure the values they measure (muscle rate, water mass, bone mass, protein, BMR, subcutaneous fat, and visceral fat)?

Question

How do modern weight measuring scales measure the values they measure (muscle rate, water mass, bone mass, protein, BMR, subcutaneous fat, and visceral fat)?

In: 4

Answer 1

And how does it differentiate between visceral and subcutaneous fat?>