The percentage of muscle mass varies between people. It will depend on several factors, including fitness, body size, and gender. There are currently no specific guidelines for what a healthy or normal muscle mass percentage should be. But a healthy body fat percentage is a useful indicator of overall body composition.

The thing is, it's hard (and not exactly helpful) to suss out what every single tissue in your body weighs. So generally, the best way to calculate muscle mass and track changes as you work to build muscle is to figure out what percentage of your body weight is lean mass and what percentage is fat.

The muscle mass and percentage muscle mass measurements show an individual with low Skeletal Muscle Mass and High Percent Body Fat (31.1%). These individuals are at risk for some of the same health complications as people who are visibly overweight, with BMI values above 25.

It encompasses muscles, bones, organs, skin, and body water, essentially everything in the body that isn't fat. Muscle mass refers explicitly to the weight of muscles in the body and is a subset of lean mass. It includes all the muscles in the body, such as skeletal muscles, cardiac muscles, and smooth muscles found in organs.