Therefore, the aim of this study was: (i) to analyze the differences in the profiles of circulating peptides regulating appetite—mainly nesfatin-1 and spexin—in children with PWS undergoing GH treatment and reduced energy intake with the profiles in healthy, non-obese children, and (ii) to evaluate the relationships between the biochemical parameters and anthropometric indices in children with PWS during GH treatment and dietary intervention. Here, SPX is linked to Prader-Willi syndrome.