X-PERT: weight reduction with orlistat in obese subjects receiving a mildly or moderately reduced-energy diet: early response to treatment predicts weight maintenance.

Aim: To determine the effect of two different levels of energy deficit on weight loss in obese patients treated with orlistat.

Methods: Patients (n=430) were randomized in a 1-year, multicentre, open-label, parallel group study conducted at 23 hospital centres and university medical departments worldwide. Obese outpatients (body mass index 30--43 kg/m(2)) aged 18--70 years with a body weight of >or=90 kg and a waist circumference of >or=88 cm (women) or >or=102 cm (men) were treated with orlistat 120 mg three times daily plus a diet that provided an energy deficit of either 500 or 1,000 kcal/day for 1 year. Orlistat treatment was discontinued in patients who did not achieve >or=5% weight loss after assessment at 3 and 6 months. The primary outcome measure was change in body weight from baseline at week 52.

Results: Reported mean difference in energy intake between the two groups (500-1,000 kcal/day deficit) at weeks 24 and 52 was actually 111 and 95 kcal/day respectively. Of the 430 patients involved in the study, 295 achieved >or=5% weight loss at both 3 and 6 months. In this population, at week 52, weight loss from baseline was similar for patients randomized to either the 500 or the 1,000 kcal/day deficit diet (-11.4 kg vs. -11.8 kg, respectively; p=0.778). After 12 months of treatment with orlistat, 84% (n=118/141) and 85% (n=131/154) of patients in the 500 and 1,000 kcal/day deficit groups, respectively, achieved >or=5% weight loss, and 50% (n=70/141) and 53% (n=82/154) of patients, respectively, achieved >or=10% weight loss. Patients in both the diet treatment groups showed similar significant improvements in blood pressure, lipid levels and waist circumference at week 52.

Conclusions: Treatment with orlistat was associated with a clinically beneficial weight loss, irrespective of the prescribed dietary energy restriction (-500 or -1000 kcal/day). Patients who achieved >or=5% weight loss at 3 months achieved long-term, clinically beneficial weight loss with orlistat plus either diet. Therefore, identifying patients who lose at least 5% weight after 3 months and who maintain this weight loss up to 6 months is a valuable treatment algorithm to select patients who will benefit most from orlistat treatment in combination with diet.