As a result of treatment, breast cancer survivors typically experience unhealthy changes in body composition (bone, muscle and fat). Treatments disrupt normal bone and energy balance resulting in bone and muscle wasting and fat gain. Premenopausal women are at greatest risk for these declines because most are thrust into early menopause from chemotherapy. Hormone manipulation therapy (i.e., tamoxifen or arimidex) may further affect these tissues. Exercise can prevent bone and muscle loss and promote fat loss. However, the ability of exercise to reverse unfavorable changes in all components of body composition in women experiencing early menopause from breast cancer treatment has not been specifically studied.