how do body fat analyzer scales work?

Public Comments

1. some send electric current through your body to calculate how much fat you have
2. i have one and it doesn't work correctly it says I have 10% more body fat then what I really do according to my doctor.
3. Based on your height and weight it gives a caluclation of how much fat you have. However, they can be flawed if you have an unusual body type.
4. it estimates the fat level by measuring the electrical conductivity of your body which isn't a very good way to do it
5. most require you to enter some information such as hieght, build, and gender. You then have to touch conductive parts of the scale. It sends a low level charge through your body to measure your electrical resistance - this is used to estimate the amount of water your body contains. Fat does not contain water - it is oil based. So, with the information you entered, your weight, and the estimated amount of water in your body, the scale calculates your percent-body fat. I have found them to be very INACCURATE. With a percent body fat of about 10%, it told me I was 17%. It also told a friend of mine, who is about 20% body fat, that he was 13%.