detectable labels include luminescent enzymatic and radioactive labels both the type of label and the position of the label can effect analog activity labels should be selected and positioned so as not to substantially alter the activity of the ghrelin analog at the ghs receptor the effect of a particular label and position on ghrelin activity can be determined using assays measuring ghrelin activity and or binding a protecting group covalently joined to the c terminal carboxy group reduces the reactivity of the carboxy terminus under in vivo conditions the carboxy terminus protecting group is preferably attached to the u03b1 carbonyl group of the last amino acid preferred carboxy terminus protecting groups include amide methylamide and ethylamide examples are provided below to further illustrate different features of the present invention the examples also illustrate useful methodology for practicing the invention these examples do not limit the claimed invention the compounds of the invention can be produced using the techniques disclosed in the examples herein as well as techniques that are well known in the art for example a polypeptide region of a ghrelin analog can be chemically or biochemically synthesized and modified examples of techniques for biochemical synthesis involving the introduction of a nucleic acid into a cell and expression of nucleic acids are provided in ausubel current protocols in molecular biology john wiley 1987 1998 and sambrook et al in molecular cloning a laboratory manual 2 nd edition cold spring harbor laboratory press 1989 techniques for chemical synthesis of polypeptides are also well known in the art see e g vincent in peptide and protein drug delivery new york n y dekker 1990 for example the peptides of this invention can be prepared by standard solid phase peptide synthesis see e g.