NPY and obesity due to melanocortin 4 receptor deficiency: For example, dietary fats activate orexigenic neuropeptides such as neuropeptide Y (NPY) and Agouti-related protein (AgRP) [15], while also attenuating anorexigenic neuropeptides like proopiomelanocortin (POMC) and cocaine- and amphetamine related transcript (CART) through gut-microbiota dependent mechanisms, contributing to hyperphagia and eventually obesity [16].