I used a tesco one last year and it gave me 2 different height, weigh and body fat readings... with a 10% difference... from 2 readings..one before and one after shopping. I think it depends on when the machine was last calibrated as to the accuracy. I was told callipers were the only reliable way to measure body fat and to get it done at the gym...I'm a big scaredy cat of the gym though. My home scales supposedly measure body fat, water etc but they are totally inaccurate...one day 35% fat... next 63% fat!! I know there is some kind of U.S military calculator online where you can put in measurements of different parts of your body..neck, waist, hips etc and it supposedly gives you a fairly accurate result? Like Kitty said though fasting has been shown to burn more fat and little muscle compared to other diets so I'm sure you would have a significant drop and it could be spot on. Love the new relaxed approach Lexie that is coming through!! xx