While prognosis for breast cancer in women has improved, adverse side effects of treatments may negatively affect body composition and bone mineral density (BMD). This study assessed body composition and BMD changes in breast cancer survivors (BCS) (n = 10, 57.9 ± 5.7 years) and age-matched women (non-cancer, n = 10, 56.5 ± 4.3 years) over a 12- to 15-month period via dual-energy X-ray absorptiometry. No differences were observed between groups at baseline except forearm BMD values were lower in BCS (BCS: 0.462 ± 0.070 g/cm² ; Control: 0.539 ± 0.052 g/cm² , p = .012). Body fat increased in both groups compared to baseline (BCS: 38.3-39.6 kg, p = .013; Control: 38.2-39.5 kg, p = .023) at the follow-up. Significant decreases in BMD at the lumbar spine, femoral neck, total femur and ulna were observed in both groups. Breast cancer survivors had a greater decrease in left femoral neck BMD. While BCS demonstrated lower baseline forearm BMD values and a greater decrease in left femoral neck BMD, both groups showed an increase in body fat and decrease in forearm BMD. These findings support the implementation of interventions to improve body composition and BMD in both BCS and women without cancer.