noun
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.
体組成計で筋肉量と体脂肪率を測る。
I measure muscle mass and body fat percentage with a body composition monitor.
定期的な運動は体組成の改善に役立つ。
Regular exercise helps improve body composition.
筋肉量 is muscle mass, one component of 体組成.
Compound of 体 (body) and 組成 (composition, structure). The term is a modern technical coinage, likely from the English 'body composition'.