In this case, “Lean Body Weight” refers to the total weight of your body if you had absolutely no fat. That is, the weight of your bones, muscles, and organs. Fat is an essential part of every healthy body. Too much fat can put a strain on your body and health, but too little fat can be fatal. Essential Body Fat is the amount of fat needed to be considered healthy.
This table, from the American Council on Exercise, shows the percentage of Essential Body Fat for various groups and categories.
By entering your weight, height and gender in the table below, you’ll have a very good idea of what you would weigh in the absence of healthy Essential Body Fat. That is, how little is TOO little. [Note: to convert height and weight between Imperial and metric measurements, click on OnLineConversion.com]