The increasing amount of patients with obesity and type 2 diabetes benefit greatly from the recently developed GIPR:GLP-1R co-agonists. These novel compounds lead to substantial weight loss, offering a revolutionary approach to patients worldwide. Although the hormone glucose-dependent insulinotropic polypeptide (GIP) was already shown by Helmholtz Munich scientists to decrease body weight via the brain GIP receptor, the underlying neurons through which GIP acts in the brain remained unknown.