section 1. Obesity phenotype -- section 2. Quantitative genetics of obesity -- section 3. Rodent models of obesity -- section 4. Nonvertebrate models -- section 5. Syndromic and monogenic human obesity -- section 6. Polygenic human obesity -- section 7. Gene-environment interaction in Human obesity -- section 8. Epigenetics in obesity -- section 9. Tissue and organ-specific gene function -- section 10. Omics technology and system biology -- section 11. Conclusion.