Orlistat, sibutramine, or combination therapy: which performs better on waist circumference in relation with body mass index in obese patients?

The aim of this study was to evaluate decrease in waist circumference in obese patients receiving different anti-obesity treatments. The study was designed as a short-term (12 weeks), open-label, and randomized trial. Eighty six patients (70 females, 81.4%; mean age 41.09+/-8.73 years, mean BMI 36.1+/-4.3 kg/m2) were randomized to four different therapy groups. The primary outcome parameters were waist circumference and body mass index (BMI). The therapy groups were a) diet+sibutramine 1 x 10 mg/d (n=22), b) diet+orlistat 3 x 120 mg/d (n=25), c) combination of diet+sibutramine+orlistat (n=20) and d) diet (n=19). Combination therapy was more effective than diet and orlistat mono-therapy (p<0.0001 for all), but not significantly superior to sibutramine mono-therapy (p=0.072) in decreasing BMI. Sibutramine mono-therapy was significantly more effective in inducing BMI decrease compared with orlistat mono-therapy (p=0.039). The association between change in BMI and change in waist circumference was strongest in the orlistat mono-therapy group (P interaction=0.003). This means that patients taking orlistat experienced more decrease in waist circumference (3.4 cm, R2=0.29) per unit decrease in BMI compared to patients under combination therapy (2.6 cm, R2=0.25, P interaction = 0.015) and patients taking sibutramine (1.8 cm, R2=0.19, P interaction=0.026). In the diet therapy group decline in waist circumference was independent of BMI (1.9 cm, R2=0.02, P interaction=0.076). Although combination therapy and sibutramine mono-therapy were more effective in decreasing BMI, reduction in waist circumference and BMI was most significantly associated with the orlistat mono-therapy group. This may hint at the possibility of orlistat inducing weight loss mainly in the abdominal area targeted to reduce cardiovascular risk.