Traditional lifestyle and dietary interventions in severely obese patients seldom lead to maintained weight loss and reduced co-morbidity, whereas bariatric surgery offers both effective weight loss and maintenance with reduced co-morbidity. Diseases benefiting from such surgery include diabetes mellitus, cardiovascular disease and cancer, and there is an associated 29–40% mortality reduction 10 years following a procedure. Economic studies estimate that obesity surgery can become cost neutral within 3.5 years of the procedure owing to reduced and avoided healthcare costs. Surgery remains a tool to help committed patients gain weight loss and health benefits. It is not an ‘easy option’ and requires the support of a multidisciplinary team including dietitians, physicians, psychologists and nurses as well as surgeons. Procedures result in a number of effects, including satiety, reduced meal volume and degrees of malabsorption. Adjustable gastric banding, sleeve gastrectomy and gastric bypass are the most common procedures used currently. As with all surgical interventions, a range of associated complications should be considered in the context of overall outcomes. It is estimated that the mortality of gastric bypass is equivalent to the 1-year mortality of untreated severe obesity. This article endeavours to summarize key aspects of this exciting field of medicine.