Obesity results from an imbalance between energy intake and energy expenditure. Drugs can shift this balance in a favorable way by reducing food intake, altering metabolism, and by increasing energy expenditure. All patients with obesity should make efforts to change their lifestyle behaviors to decrease energy intake and increase physical activity. Lifestyle modifications also should be a component of all other levels of therapy. Pharmacotherapy can be a useful adjunctive measure for well-selected patients. Anti-obesity pharmacological treatment is indicated when the patient's body mass index (BMI) is >25 kg/m² or when the patient's BMI is >23 kg/m² with co-morbidities such as diabetes, hypertension, hypercholesterolemia, and coronary artery disease. Obesity is a chronic disease that requires long-term therapy for successful long-term weight management. Often, the patients regain their lost weight after therapy is discontinued, so it should be stressed that obesity is not a curable disease, and thus the maintenance of the reduced weight is very important. Obese patients must be examined in detail regarding mood, obesity-related complications or conditions, current medications, eating habits, and history of drug side-effects. The physicians' choice for anti-obesity medications is based on both the patient's medical conditions and long-term safety and efficacy of antiobesity drugs.