The effect of weight loss on estimated breast cancer risk, sex hormone binding globulin (SHBG), total and free estradiol levels was evaluated. Increasing weight loss reduced upper body fat distribution progressively. Women with a family history of breast cancer who lost more than 7.0 kilograms decreased their estimated breast cancer risk by 25.7% while women without such a family history decreased their risk by 42.8%. A significant (P<0.001) increase in SHBG with a 4.0 to 7.4 kg weight loss was seen in both pre and postmenopausal women (P<0.05). No significant change in total or free estradiol levels was observed.