The overweight and obesity epidemic affects approximately 1.6 millions of people worldwide. Obesity is a chronic condition, associated with premature death, co-morbidities, risk factors for main cardiac disease, stigmatization and significant economic costs. The causes of obesity are complex and include the interplay of environmental, social, economic and genetic factors. Besides fat-rich diets also play a significant role in the etiology of obesity. Correct diet orientation associated with physical exercise usually did not lead to expected result in weight loss and maintenance. Pharmacological therapy has been proposed as an adjunct to achieve the ideal weight. Orlistat acts in reduction of lipids absorption by inhibition of gastric and pancreatic lipases in gastrointestinal tract leading to sustained weight loss. This is a double blind study, randomized, of 2 weeks. The aim of this study was evaluate the intestinal lipase blockade by decrease of fat absorption of fecal fat after treatment with two commercials formulations of Orlistat in obese patients.