body composition
Technical term used in health, fitness, and medical contexts to refer to the proportions of fat, muscle, bone, and water in the body.
I measure muscle mass and body fat percentage with a body composition monitor.
Regular exercise helps improve body composition.
筋肉量 is muscle mass, one component of 体組成.
body composition monitor; body fat scale
Compound of 体 (body) and 組成 (composition, structure). The term is a modern technical coinage, likely from the English 'body composition'.