how can special body scales detect what you are made of, like body fat?

Question

I have some physical understanding, but how can they tell my body fat % and how accurate os that?

In: Technology

Answer 1

It uses something called bioelectric impedance. Fat and muscle conduct electricity differently because muscle has more water content while fat is an insulator (slows down electricity). The little silver parts you stand on send out a super small electric signal that you can’t feel but it measures how quickly it goes out one silver piece and back into the other. Since it knows how fast it goes through water/muscle and fat, it can estimate how much of each it went through. It also uses characteristics such as age to help it be more accurate. BIA is accurate to within roughly 3-5% under perfect conditions, but how hydrated you are, your body temp, etc can alter results quite substantially.