The invention provides a peptide based on biologically active CCK-8 having improved characteristics for the treatment of obesity and/or type 2 diabetes wherein the primary structure of CCK-8 is: Asp.sup.1Tyr.sup.2(SO.sub.3H)-Met.sup.3Gly.sup.4Trp.sup.5Met.sup.6Asp.sup- .7Phe.sup.8amide (SEQ ID NO:1) and wherein the peptide has at least one amino add substitution and/or modification and is not Asp.sup.1-glucitol CCK-8. The invention also provides the use of the peptide in the preparation of a medicament to inhibit food intake, induce satiety, stimulate insulin secretion, moderate blood glucose excursions, enhance glucose disposal and/or exhibit enhanced stability in plasma compared to native CCK-8 and/or for treatment of obesity and/or type 2 diabetes.