Long-term weight loss maintenance, sex steroid hormones, and sex hormone-binding globulin

Objective: We tested the effects of weight loss on serum estradiol, estrone, testosterone, and sex hormone-binding globulin (SHBG) in overweight/obese women 18 months after completing a year-long, 4-arm, randomized-controlled dietary weight loss and/or exercise trial. Methods: From 2005 to 2008, 439 overweight/obese, postmenopausal women (BMI > 25 kg/m(2)), 50 to 75 years, were randomized to a year-long intervention: diet (reduced calorie, 10% weight loss, N = 118), exercise (225 min/wk moderate-to-vigorous activity, N = 117), combined diet + exercise (N = 117), or control (N = 87). At 12 months, 399 women provided blood; of these, 156 returned at 30 months and gave a blood sample. Hormones and SHBG were measured by immunoassay. Changes were compared using generalized estimating equations, adjusting for confounders. Results: At 30 months, participants randomized to the diet + exercise intervention had statistically significant increases in SHBG levels versus controls (P = 0.001). There was no statistically significant change in SHBG in the exercise or diet intervention arms. Hormone levels did not vary by intervention arm from baseline to 30 months. Participants who maintained weight loss at 30 months had statistically significantly greater decreases in free estradiol and free testosterone (P-trend = 0.02 and P-trend = 0.04, respectively) and increases in SHBG (P-trend < 0.0001) versus those who did not have sustained weight loss. Levels of other analytes did not vary by weight loss at 30 months. Conclusions: Sustained weight loss results in reductions in free estradiol and testosterone and increases in SHBG 18-month post-intervention.