The gut-brain axis is one of the main regulators of appetite (Cummings et Overduin). Responsible for this interaction are among others the appetite-controlling gut peptides: ghrelin and PYY. Ghrelin is produced primarily in the endocrine cells of the oxyntic mucosa of the gastric fundus and was originally described as a potent endogenous GH stimulating factor (Kojima et al, Date et al). It induces short-term food intake and long-term adiposity by acting at the hypothalamus (Tschop et al, Nakazato et al). Ghrelin is highly conserved throughout the evolution and responsible for many central and peripheral endocrine and non-endocrine effects (van der Lely et al, Ghigo et al). Peptide YY or PYY is mainly produced in the terminal ileum and colon and characterized as an agent inhibiting gastrointestinal motility and appetite PYY(3-36) has been shown only recently in humans (Lundberg et al, Batterham et al. 2002). Upon infusion of PYY(3-36) subsequent food consumption was reduced in both lean and obese subjects (Batterham et al. 2003).