The Zone Diet Body Fat Calculator will not only provide you with your Body Fat Weight and Lean Body Mass, but it will also determine the amount of protein you need each day and the number of Zone Blocks you should consume. All of this will be explained after you enter your measurements.
A rapid way to determine your lean body mass is simply to use a tape measure and a scale. You should make all measurements on bare skin (not through clothing) and make sure that the tape fits snugly but does not compress the skin and underlying tissue. Take all measurements three times and calculate the average. All measurements should be in inches.