NPY and obesity due to melanocortin 4 receptor deficiency: For instance, studies have reported that dietary fats activate orexigenic neurons coexpressing neuropeptide Y (NPY)/Agouti-related protein (AgRP) while also attenuating anorexigenic neurons coexpressing proopiomelanocortin (POMC)/cocaine- and amphetamine-related transcript (CART), which contributes to hyperphagia and eventually leads to obesity [19].