Obesity, which is becoming a lifestyle disease, is a significant social problem due to its growing frequency and its complications, primarily cardiovascular diseases. The recommended conservative treatment of obesity, consisting in the use of a weight reduction diet and physical activity, is often not effective or the effect of these actions does not last long. Bariatric surgery is an emerging field of surgery that can be used to treat obesity in a selected group of patients. Different operative methods of bariatric procedures are available. They allow one to achieve a significant weight loss. However, their application requires proper preparation of the patient before surgery and changes in eating habits and often chronic use of dietary supplements after surgery. This method of treatment should be considered in patients in whom conservative treatment has not produced the desired effect. Bariatric treatments are aimed not only at achieving weight loss, but also at improving the course of diseases often coexisting with obesity, such as type 2 diabetes or hypertension.