Sex steroids and gender differences in muscle, bone, and fat

Sex steroids, comprising of the androgens, estrogens, and progestogens, are fundamentally important to the development of muscle, bone, and fat across the life course. Each has roles that differ between these tissues, the male and female sexes, and developmental stage. It is the differential production of sex steroids and expression of their receptors that mediates much of the pubertal development in muscle, bone, and fat, which in turn determines the typical dimorphic sexual phenotypes. It is similar to how this differential production changes over time that is responsible for much of the typical sex-specific changes seen with normal aging. This chapter considers the sex-specific production of sex steroids and their effects upon each muscle, bone, and fat. It additionally covers the developmental changes in sex steroid production, and how this contributes to age-related changes in these three tissues.