Body fat composition describes the share of a person’s total body weight made up by adipose tissue, with the remainder comprising muscle, bone, organs, and water. It is commonly expressed as a body fat percentage and measured through techniques such as bioelectrical impedance, skinfold thickness, air-displacement plethysmography, or DEXA scanning. Healthy ranges differ by sex and age: women carry more essential fat than men, and acceptable percentages rise modestly with age. Unlike the body mass index, which cannot distinguish fat from muscle, body fat composition gives dietitians and sports nutritionists a clearer picture of adiposity, energy reserves, and cardiovascular risk linked to excess fat.