Energy balance and eating behaviour are regulated by leptin-melanocortin system that includes afferent signals from peripheral tissues (leptin, ghrelin, insulin, blood glucose), integrative first order neurons in arcuate nucleus, and second order effector neurons in paraventricular and intermediolateral nuclei that express melanocortin receptors. Components of this system have individual genetic a nd epigenetic coding, with partial impact of environmental factors.
Abnormal eating behaviour may be due to pathogenic variants of genes encoding key molecules of eating behaviour. Monogenic obesity is characterized by early-onset obesity - in some cases with insulin resistance and/or neurodevelopmental delay.