We review the years developments in the field of psychological support and assessment of patients undergoing metabolic surgery. In the move away from the gatekeeping role of the psychiatrist or psychologist within multi-disciplinary weight management teams, we review the evidence for psychological predictors of outcome after metabolic surgery. We review the long term psychological outcomes after metabolic surgery. There is a lack of parity of metabolic surgery being offered to patients with serious mental illness, despite growing evidence that patients with serious mental illness have a high mortality rate associated with their obesity and metabolic illness. The critical need for post-operative psychological support in the light of weight regain and potential negative psychological outcomes from surgery is addressed. The evidence for effective psychological interventions, including the optimal timing and cost-effective delivery methods thereof is reviewed. The need for longer term follow up and de-emphasis on weight outcomes in trials is highlighted.