Bariatric surgery can effectively reduce body weight and treat obesity associated metabolic diseases such as diabetes mellitus. There are also benefits for an individual's functional status and psychological health. A multi-disciplinary evaluation should be offered to the individual as the first essential step in considering bariatric surgery as a treatment. This evaluation should include a thorough medical assessment, as well as psychological and dietetic assessments. In this best practice article, we outline the current recommendations for referral for bariatric surgery. We also present the data for pre-operative assessment before bariatric surgery, with particular reference to cardiovascular disease and obstructive sleep apnoea. We describe the literature on outcomes after bariatric surgery, including the results for mortality, weight loss, remission of diabetes and associated endocrine disorders such as hypogonadism. Within this review, we will illustrate the impact of bariatric surgery on self-image, psychological health and perceived health and functional status. Finally, we briefly detail the potential complications of bariatric surgery, and offer advice on post-operative care and surveillance.