Inclusion Criteria:  Postmenopausal women, postmenopausal is defined either by:  A. Age ≥ 55 years and one year or more of amenorrhea. B. Age < 55 years and one year or more of amenorrhea, with an estradiol assay < 20 pg/ml.  • Patients with breast cancer indicated for hormonal treatment with aromatase inhibitors (overweight 30 > BMI ≥ 25, obese BMI ≥ 30 kg/m2 and non obese BMI between 18 and 25 kg/m2).  Exclusion Criteria:  • Diabetic patients.  Patients with metabolic syndrome. Patients with last menstrual cycle less than one year ago. Patient with conditions predispose to acidosis (heart failure, renal failure). Ovarian radiation treatment with luteinizing hormone-releasing hormone (LH-RH) agonist (goserelin acetate or leuprolide acetate) is not permitted for induction of ovarian suppression.