As much as I am somebody who is for objective, brutally honest, even "harsh" body fat measurements, you are not 20%. The scale you used uses bioelectrical impedance. This tool is about as effective at establishing BF percentage as throwing darts on a target with numbers ranging from 1% to 40%!!!
You level of hydration/dehydration can change the results by up to 10% in a matter of minutes for example!
And the more muscle you have, the more imprecise it is.
I once had a hockey player I trained call me, almost crying, because he just got tested at 19%... and the guy had veins on his abs!
Pat, the bodybuilder in my "great video" thread was even tested at 18% when he was in contest shape!
Bottom line, that equipment sucks.