A system for measuring percentage of body fat for a user. The system has: structure for measuring body hydration and generating a signal representing a measured hydration value; structure for selectively changing the measured hydration value to an adjusted hydration value based upon a first parameter to thereby reflect more accurately an actual hydration value for the user and generating a signal representing the adjusted hydration value; and structure for measuring body fat percentage using the signal representing: a) the measured hydration value; or b) the adjusted hydration value in the event that the structure for selectively changing the measured hydration value changes the measured hydration value based upon the first parameter.