Epidemiological studies suggest a protective influence of obesity against postmenopausal bone loss. Lower risk of osteoporotic fractures was described in obese patients. However there were only a few studies which examined the effect of weight reduction on bone metabolism and results of these studies are controversial.
The aim of the study was to evaluate the influence of weight reduction program using Orlistat on bone metabolism in perimenopausal women. Twenty obese women with simple obesity and without concomitant diseases (BMI 37.1 ± 3.0 kg/m², mean age 49.8 ± 4.6 yrs) were enrolled into this study. The control group consisted of 20 healthy women (mean age 53.5 ± 5.4 yrs, BMI 24.1 ± 2.2 kg/m²). All patients have participated in a 3-month weight reduction therapy that consisted of: a 1000-1200 kcal/day balanced diet (daily calcium consumption about 500 mg), Orlistat 3x120 mg a day and regular physical exercises. Before the weight reduction therapy and after 10% reduction of body weight, serum concentrations of PTH, 25-(OH)-D₃, total calcium and phosphorus, total cholesterol were assessed. Dual energy x-ray absorptiometry (DEXA method) of lumbar spine and femoral neck, measuring BMD was performed once, after a 3-month weight reduction therapy using Lunar DPXL. All these measurements were performed only once in control subjects.
After a 3-month weight reduction program in patients treated with Orlistat the mean weight loss was 11.6 ± 5.1 kg which is 12.1 ± 4.78%. BMI decreased from 37.1 ± 3.0 kg/m² at baseline to 32.6 ± 2.7 kg/m² post-treatment. The body weight reduction resulted in significant decrease of body fat and total cholesterol concentration. In obese subjects serum concentration of 25-(OH)-D₃ was significantly lower and serum concentration of PTH was significantly higher in comparison to healthy controls, both before and after weight reduction therapy.Serum concentration of PTH, 25-(OH)-D₃, total calcium and phosphorus did not change significantly after therapy with Orlistat.
Conclusion: 3-month weight reduction program using Orlistat did not influence significantly bone metabolism.