Preoperative interventions aimed at patients referred for bariatric surgery continue to divide funders, commissioners, and practitioners alike. A number of preoperative interventions and variables have been used to influence patient selection. Many of these are believed to lead to better postoperative outcomes by helping target a limited resource (bariatric surgery) at those most likely to benefit. Inevitably, this leads to competition amongst patients and some being denied benefits of surgery. There is a risk that these strategies for resource allocation may actually deprive the most vulnerable and those most in need. This review examines evidence and justification behind popular preoperative interventions for patients being considered for bariatric surgery patients in the light of published English language scientific literature.