Genetic mechanisms are relevant for both body weight regulation and eating disorders (e.g. anorexia nervosa, AN). Although genome-wide association studies (GWAS) have so far identified about 100 chromosomal regions that influence body weight, only a small part of the variance could be explained by molecular genetic factors. For AN GWAS up to now did not reveal genome-wide significant loci. There are first hints for epigenetic mechanisms involved in the described phenotypes. Epigenomics can improve our understanding of the regulation of body weight including hunger (AN) and overnutrition (obesity). Since the prenatal phase is characterized by dramatic epigenetic changes, it can be regarded as vulnerable period for the epigenotype. Adult health and disease depend on prenatal and early postnatal development. Gene expression markers that are imprinted during this phase can be heritable at the cellular level. These markers can be altered by environmental factors. Altered epigenetic profiles had been described for obese individuals. In mice it was shown that an epigenetic modification of an obesity gene locus had been transferred to the next generation. The year to come will show whether the combined analysis of epigenomic and GWAS data will deepen our understanding of the underlying biological mechanisms.