What is Lean Muscle Mass?

Lean Mass is everything else that makes up your weight (besides fat). It includes muscle, bones, organs, water, and all non-fatty tissues.

There is a gender difference in lean mass levels. Thanks to much higher levels of testosterone, men have a greater amount of muscle mass than women. 

Muscle also weighs more than fat, but it takes up much less space. For example, one pound of muscle is much smaller than one pound of fat. So, as you exercise consistently and build up strength, your total body weight may actually increase. This can be confusing (and sometimes scary), but you are gaining muscle, while maintaining or even losing fat.

Look for gains: Your lean mass can be calculated by subtracting your total fat (as a percentage or in actual pounds) from your total weight. This number will probably be relatively stable, or increase over time, as long as you are exercising. Gains in muscle mass will increase your metabolism, thus enabling you to burn more calories during every activity--even sitting! So, while you do want to lose fat, setting a goal of increasing your muscle mass will help you get there.

Body Benefit: Muscle increases boost your metabolism and fitness levels