TLR4 and obesity due to melanocortin 4 receptor deficiency: In particular, saturated fatty acids (SFAs) can promote the development and progression of several noninfectious and inflammatory diseases, such as NAFLD, atherosclerosis, insulin resistance, and obesity, by activating Toll-like receptor 4 (TLR4) signaling in rodent models, promoting the inflammatory aspects of metabolic syndrome [7,9].