The objective of this case report is to present a pharmacologic strategy for treatment of adolescents with anorexia nervosa (AN) and low bone mineral density (BMD). We present a 17.5-year-old girl with a 3-year history of AN and longstanding inability to optimize nutrition and gain weight, and a decrease over time in her already low BMD. A year after treatment with the 17-β estradiol patch (100 mcg twice weekly) with cyclic oral progesterone (2.5 mg medroxyprogesterone acetate daily for days 1-10 of every month), her spine and hip BMD Z-scores improved, and a further decrease was prevented. This novel treatment is a consideration for girls with AN at greatest risk for low BMD. Adolescents with AN are at risk for low BMD, and the most effective treatment is weight and menses restoration, which can be difficult to attain and to sustain. Recent studies have shown promising results with pharmacological therapy for low BMD in AN. This article discusses current concepts related to bone loss in AN, and new pharmacologic considerations for adolescents at greatest risk for low BMD.