The disclosure provides chimeric polypeptides and nucleic acid molecules encoding chimeric polypeptides. Also provided are pharmaceutical compositions and methods of treatment for diseases and disorders including lipodystrophy, dyslipidemia, hyperlipidemia, overweight, obesity, hypothalamic amenorrhea, Alzheimer's disease, leptin deficiency, fatty liver disease or diabetes (including type I and type II). Additional diseases and disorders which can be treated by the compounds and methods described herein include nonalcoholic steatohepatitis (NASH) and nonalcoholic fatty liver disease (NAFLD), metabolic syndrome X and Huntington's Disease.