All FI must meet the requirements outlined in the medicare intermediary manual. Fiscal intermediary services organizations (FISOs) are regulated by the Office of Insurance Regulation.
Fat free mass consists of water (72%) protein (21%) and bone minerals (7%) typically an adult has only 3-4kg bodyweight from bone. Fat mass varies considerably between individuals, in terms of absolute amount. Fat mass consists of 20% water and 80% adipose tissue. Healthy ranges of body fat range from between 14-20% for men, a percentage of greater than 25% is considered to be unhealthy and puts the individual at an increased risk of obesity related illness. Healthy ranges for women range between 17-24% where a level of 30% body fat is considered unhealthy and at a level of increased risk.
Because your fat in your body has a lot of water in it, you have to first know how much fat you have in your body before you can then figure out what your healthy water content is. That is, if you say have 33% fat in your body, then you only need another 37% of water alone, because you have water in the fat. The scales don't count fat water as water, otherwise your numbers would get very confusing :) Luckily, every scale that I've seen that measures water also measures fat, at the same time!