Higher Bone Mineral Density in Obesity Masks Impaired Bone Remodeling and Disproportionate Musculoskeletal Adaptation in Young Women

Obesity is a multifactorial disease characterized by excessive adiposity that influences bone remodeling through increased mechanical loading, chronic low-grade inflammation, and sedentary behavior. While obesity is linked to structural skeletal changes, its precise impact on bone mineral density (BMD) and bone remodeling in humans remains controversial, particularly in young women. This is particularly relevant because the majority of studies have investigated young women, in whom many of the observed skeletal alterations are attributable to aging rather than obesity per se. This study investigated the impact of increased adiposity on total, lumbar spine, and femoral neck BMD in 54 young Brazilian women with 18-40 years. Body composition and BMD were assessed by DXA, and plasma markers of bone formation and resorption were analyzed. Associations among adiposity, lean mass, BMD, and bone turnover markers were examined. Women with obesity exhibited higher total and regional BMD and greater lean mass than women without obesity. However, adjusting bone and lean mass for fat mass revealed a musculoskeletal imbalance. In addition, obesity was associated with a suppressed bone turnover profile; these women presented lower circulating levels of the formation markers P1NP and osteocalcin, alongside elevated resorption markers CTX-I and RANK-L/OPG. Ultimately, these findings demonstrate that bone remodeling is compromised despite an apparent increase in bone mass. Obesity in young Brazilian women is associated with higher BMD and lean mass; however, these findings may mask underlying detrimental alterations in bone remodeling. The observed imbalance between bone formation and resorption demonstrates that increased density does not reflect improved skeletal health, but rather compromised bone quality and structural fragility.