Are you an adult who is overweight or obese and has serious health problems because of your weight? Have you tried diet and exercise but haven't been able to achieve significant weight loss? If you answered yes to these questions, then a prescription weight-loss drug might be an option for you.You should know, however, that prescription weight-loss drugs are used in addition to — not instead of — diet and exercise.You should be on a low-fat diet (less than 30% of your daily calories from fat) before taking orlistat.Also, take a multivitamin at least 2 hours before or after taking orlistat, because the drug temporarily makes it harder for your body to absorb vitamins A, D, E, and K.