Effects of Postmenopausal Hormone Replacement Therapy on Body Fat Composition

Aim: To evaluate the effects of different types, regimens and administration routes of hormone replacement therapy (HRT) on body fat composition indices in postmenopausal women at increased risk of anthropometry-related cardiovascular disease (CVD).

Methods: Fifty-nine postmenopausal women (aged 41-57 years, mean +/- standard deviation: 49.9 +/- 3.8 years) with body mass index (BMI) > or =25 kg/m(2) participated in this 6-month, prospective, randomized single-blind study. Subjects were assigned into three groups and received transdermal estradiol (E2)/norethisterone acetate (NETA) (50 microg E2 daily for 14 days followed by 50 microg E2/0.25 microg NETA daily for 14 days; transdermal group, n = 19), transdermal continuous E2/oral medroxyprogesterone acetate (MPA) (50 microg E2/5 mg MPA daily; transdermal/oral group, n = 19) or oral continuous E2/NETA (1 mg E2/0.5 mg NETA daily; oral group, n = 21). Anthropometric indices (body weight, height, and hip and waist circumferences) were measured, and BMI and waist-to-hip ratio (WHR) were calculated, before and after treatment. Also, the thickness of subcutaneous abdominal fat was measured by ultrasound. Depending on waist circumference (WC), the subjects were divided into two risk groups: increased-risk group with WC <88 cm (n = 32) and high-risk group with WC > or =88 cm (n = 27). Also, the effects of HRT were evaluated separately in subjects with median subcutaneous fat of <33 mm (n = 29) and those with median subcutaneous fat of > or =33 mm (n = 30).

Results: Overall, all three types of HRT caused a significant decrease in both WC and subcutaneous fat (p < 0.001), and also in WHR (p < 0.05). There was no significant difference in baseline (p > 0.05) and final values (p > 0.05) between HRT groups. In each group, all types of HRT significantly decreased WC and subcutaneous fat (transdermal group: p < 0.001 and p < 0.05; transdermal/oral group: p < 0.001 and p < 0.01; oral group: p < 0.001 and p < 0.001, respectively), while body weight, BMI and WHR changed only insignificantly (p > 0.05). In the increased-risk group, body weight increased significantly (p < 0.05) while WC and subcutaneous fat decreased significantly (p < 0.001 and p < 0.001). As for the high-risk group, there was a significant decrease in WC and subcutaneous fat (p < 0.001, p < 0.001) while the remaining parameters did not change significantly. However, BMI showed a tendency to increase in the increased-risk group, while there was a decrease in all measurements in the high-risk group. Regardless of the drugs used and baseline subcutaneous fat, WC and subcutaneous fat decreased significantly at the end of the treatment (subcutaneous fat <33 mm: p < 0.001 and p < 0.01; subcutaneous fat > or =33 mm: p < 0.001 and p < 0.001, respectively).

Conclusions: The three different types of HRT have comparable effects on central fat tissue in women at increased risk of anthropometry-related CVD. Indeed, the three combinations of HRT reduced fat tissue in the central part of the body. However, the overall effect of HRT was more marked in women with WC > or =88 cm and subcutaneous fat > or =33 cm. Whether HRT increases body weight depends on the body composition indices of individuals before treatment.