CCK and obesity due to melanocortin 4 receptor deficiency: Furthermore, CCK in a stabilized form resistant to degradation in the GI tract is effective at reducing food intake and body weight in DIO rodents (Pierson et al., 1997; Irwin et al., 2012, 2013b), and activating CCKA receptors enhances the anti-obesity properties of GLP-1 agonists, amylin, and leptin (Trevaskis et al., 2010, 2015; Irwin et al., 2013a, 2015).