TLR4 and Obesity: In obesity, hypothalamic microglia are activated by elevated circulating saturated fatty acids via the Toll-like receptor 4 (TLR-4)/NF-κB signaling pathway, leading to the polarization of microglia into a pro-inflammatory M1 macrophage-like phenotype, which exacerbates local inflammation in the hypothalamus (Lively and Schlichter, 2018).