This invention provides methods of modifying feeding behavior, including increasing or decreasing food consumption, e.g., in connection with treating obesity, bulimia or anorexia. These methods involve administration of compounds are selective agonists or antagonists or the Y5 receptor. One such compound has the structure: In addition, this invention provides an isolated nucleic acid molecule encoding a Y5 receptor, an isolated Y5 receptor protein, vectors comprising an isolated nucleic acid molecule encoding a Y5 receptor, cells comprising such vectors, antibodies directed to the Y5 receptor, nucleic acid probes useful for detecting nucleic acid encoding Y5 receptors, antisense oligonucleotides complementary to any unique sequences of a nucleic acid molecule which encodes a Y5 receptor, and nonhuman transgenic animals which express DNA a normal or a mutant Y5 receptor.