These are wonderful scales and fantastic value for money. Two minutes fiddling around had batteries installed, a profile (age, height, gender) set up and I was ready to go. These scales measure your body mass and have your height so they are able to automatically calculate give a BMI reading, however, as we know BMI is very crude as a person heavy with muscle is officially classed as obese. This is not a problem however as they also use electrical impedance (essentially how resistant your body is to currents flowing from hand to hand and foot to foot and hands to feet) to calculate the composition of your body. Twenty seconds after you hop on you know your weight, your BMI, your fat content (visceral and sub-cutaneous) and your muscle levels. This means you can do the following:
1. diet and check that you are not losing muscle, but fat (if you lose muscle then the weight comes back with interest, as only muscle can burn calories)
2. make these part of an exercise regime (as I do) and track whether the changes in weight are due to eating too much or increasing muscle mass and then modify to take account.
3. use them as normal bathroom scales, but with the ability to ensure that increasing weight is not drifting into dangerous levels.
I think these are great, but they can burst your bubbles (I genuinely though the weight I had put on was muscle - it wasn't). A word of caution though, it is quite possible to get obsessive with these, they are far better used at intervals of a week or more than daily.