A transgenic non-human animal is disclosed, the animal having a nucleic acid inserted in its genome, wherein the presence of the inserted nucleic acid in the genome of the animal results in expression of an agent, which agent is encoded by a nucleotide sequence in the genome of the animal, and wherein the agent inhibits the ability of a leptin to activate an Ob-Rb receptor. Uses of the animal and methods of identifying compounds using the animal are also disclosed.