Unfortunately you might as well just guess a number when it comes to using scales to workout body fat. Electrical impedance is not an accurate way of doing it. It's semi useful for looking at trends but not for getting an actual measurement.
What was that you were saying about being nearly 19 stone a couple of weeks ago. I think you should concentrate on your own weight issues instead of criticizing mine. No offense but people who live in glass houses shouldn’t throw stones.