If you have health problems related to your obesity, your doctor may recommend medication as a way to lose weight, in addition to diet and exercise. Three common options are orlistat, phentermine and sibutramine. Orlistat, also marketed under the brand name Xenical, blocks 30 percent of dietary fat from being absorbed by the body. Phentermine and sibutramine both suppress appetite. A diagnosis of obesity can feel overwhelming, but there is help for this condition.