Computed Tomography Study of the Effect of Orlistat on Visceral Adipose Tissue Volume in Obese Subjects

Background: Obesity has become a major public heath problem worldwide. Objectives: To examine the effect of orlistat in promoting weight loss and its specific effect on visceral adipose tissue and subcutaneous adipose tissue as evaluated by computed tomography. Methods: A prospective case series study of 10 obese subjects was conducted. The 6 women and 4 men, age 50-67 years (mean 59 +/- 8 years), had a mean body mass index of 34.1 +/- 3.2 kg/m(2). All subjects were prescribed a mildly hypocaloric diet (600 kcal/day deficit). In addition, all subjects were treated with orlistat 120 mg 3 times a day for 20.1 +/- 7 weeks. Results: The subjects had lost approximately 8.2 kg each, or 8.4% of their initial body weight. Mean body weight decreased from 98 +/- 13 to 89.8 +/- 13.6 kg at the last follow-up visit (P = 0.0001); mean BMI decreased from 34.1 +/- 3.2 to 30.3 +/- 3.9 kg/m(2) (P = 0.0001), and mean waist circumference from 113.8 +/- 11.4 to 107.6 +/- 10 cm (P = 0.0006). Mean total abdominal adipose tissue volume, evaluated by computed tomography, decreased from 426 +/- 104.3 to 369.8 +/- 99.6 mm(3) (P = 0.0001). Mean abdominal SAT volume decreased from 251.1 +/- 78.8 to 224 +/- 81.1 mm(3) (P = 0.006), and mean abdominal VAT volume decreased from 176 +/- 76.7 to 141.6 +/- 67 mm(3) (P = 0.0001). Thus, the total abdominal adipose tissue volume for the whole group decreased by 15.4%, and most of this decrease was attributable to the reduction in VAT (24.8%) as opposed to SAT (only 12% reduction) (P = 0.03). The weight reduction that occurred during the study was accompanied by a statistically significant reduction in levels of total cholesterol, low density lipoprotein-cholesterol, triglycerides, and fasting blood glucose. Conclusions: Our results demonstrate the effect of orlistat in reducing human visceral adipose tissue as evaluated by CT. The benefit of the treatment is further supported by the statistically significant reduction in cardiovascular risk factors. IMAJ 2010; 12: 199-202