BDNF and obesity due to melanocortin 4 receptor deficiency: Intestinal dysbiosis has been reported to be associated with chronically increased leptin levels and decreased sensitivity to leptin, through the induction of the suppressor of cytokine signaling 3 (SOCS3) and the suppression of the brain-derived neurotrophic factor (BDNF) expression in the hypothalamus (Schéle et al., 2013), and decreased expression of obesity-suppressing neuropeptides in the central nervous system (Yao et al., 2020).