Responses to Appetite and Taste in the Brain Circuits That Control Eating Behaviour

This is an observational study aiming to gain insight into brain structure and the neural networks that control taste and eating behaviour in patients with severe obesity undergoing a primary sleeve gastrectomy (SG) or a lifestyle intervention for weight loss compared with normal weight individuals using functional magnetic resonance imaging (fMRI). Drops of liquid foods and a control solution will be delivered to the participants' mouth during fMRI scanning. Body weight, gut hormones from serial blood samples, appetite scores and taste will be assessed at each study visit.