Bariatric surgery is the most effective method of achieving long-lasting weight loss and improving metabolic and cardiovascular outcomes in selected obese patients (i.e. with body mass index [BMI] ≥ 40 kg/m2 without coexisting morbidities or BMI ≥ 35 kg/m2 with severe obesity-related diseases). As the epidemic of obesity grows, it is estimated that by 2030 around 11% of the population will be severely obese. Therefore, the number of bariatric procedures performed increases year after year, and it reached 179,000 in 2013. Bariatric procedures can be divided into three main types: restrictive, malabsorptive, and mixed procedures. While, careful multi-disciplinary preoperative assessment of the patient is an inseparable part of bariatric procedures, there is also a need for multi-disciplinary management after bariatric surgery. This should include surveillance by an internist, surgeon and registered dietician. However, treatment outcome is primarily dependent on the patient’s compliance and awareness of the need for regular follow-up. This cannot be achieved without proper behavioral and psychological support, as it is as vital as other surveillance aspects. In this review we discuss early and late complications of bariatric surgery, its influence on obesity-related diseases, and changes in body composition and metabolism. According to recent guidelines and recommendations of American and European medical societies, we summarize available standards of post-bariatric management.