593810 Discloses a compound having the formula R1-X-Z-R2 wherein the peptide has the formula HIS-SER-GLN-GLY-THR-PHE-THR-SER-ASP-THY-SER-LYS-TYR-LEU-ASP-SER-LYS-ALA-ALA-HIS-ASP-PHE-VAL-GLU-TRP-LEU-ARG-ALA and variations thereof. Also describes the use of the compound in preventing weight gain, promoting weight loss.