The physiology of altered eating behaviour after Roux‐en‐Y gastric bypass

New Findings What is the topic of this review? This review describes the altered eating behaviour after Roux‐en‐Y gastric bypass (RYGB) and discusses results of experiments designed to translate findings from animals into humans by performing similar types of direct behaviour‐testing experiments. What advances does it highlight? Roux‐en‐Y gastric bypass patients often report a decrease in preference for calorically dense food items, such as desserts, while reporting an increased preference for fruits and vegetables. After RYGB surgery, rats show a reduced preference for higher concentrations of sucrose (sweet) or fat (Intralipid®). Conditioned taste aversion may contribute to the reduction in fat preference after RYGB. After Roux‐en‐Y gastric bypass, patients are less willing to work for a chocolate reward than before the operation in a so‐called progressive ratio test. Obesity and its related comorbidities can be detrimental for the affected individual, as well as constituting a major challenge to public health systems worldwide. Currently, the most effective treatment option leading to clinically significant and maintained body weight loss and reduction in obesity‐related morbidity and mortality is obesity surgery, which is recommended for patients with a body mass index of >40 kg m–2, or >35 kg m–2 if obesity‐associated comorbidities, such as type 2 diabetes mellitus, are present. This report focuses on the altered eating behaviour after the most common of these operations, the Roux‐en‐Y gastric bypass. Animal and human experiments designed to understand the underlying physiological mechanisms of altered taste and appetite are discussed.