This involvement of the ghrelin system in different physiological processes has sparked a discussion about its role in a variety of pathological conditions like obesity and eating disorders, but also addictive disorders as well as anxiety disorders, PTSD and mood disorders (for review see Labarthe et al., 2014; Wittekind and Kluge, 2015; Bali and Jaggi, 2016; Stievenard et al., 2016; Jiao et al., 2017; Shi et al., 2017). Here, GHRL is linked to obesity due to melanocortin 4 receptor deficiency.