Orlistat: selective inhibition of caloric absorption can affect long-term body weight

Orlistat is a novel, noncentrally acting antiobesity agent that selectively inhibits gastrointestinal lipase activity, thereby reducing the absorption of dietary fat by approximately one-third. In a series of 1- and 2-yr randomized, placebo-controlled trials of obese subjects, treatment with orlistat in combination with a mildly calorie-restricted diet consistently produced significantly greater mean weight loss than diet alone. More orlistat-treated subjects than placebo recipients achieved clinically meaningful weight reduction (> or =5% or > or =10% of initial body weight) after 1 and 2 yr. Orlistat was also associated with a significant reduction in the regain of lost weight during long-term treatment. In addition, orlistat therapy resulted in significant improvements in several cardiovascular risk factors including serum total and low-density lipoprotein-cholesterol, serum insulin levels, systolic and diastolic blood pressure, and waist circumference. Furthermore, obese subjects with type 2 diabetes achieved a significantly greater decrease in body weight with orlistat compared with placebo, as well as significant improvements in HbA1c and fasting glucose levels. Among subjects with impaired glucose tolerance, orlistat compared with placebo reduced the proportion who developed type 2 diabetes. Conversely, orlistat increased the proportion of subjects who achieved a normalization of glucose tolerance. Orlistat acts locally in the gastrointestinal tract and is only minimally absorbed. In long-term clinical trials, orlistat was well tolerated by both diabetic and nondiabetic subjects.