FFAR2 and obesity due to melanocortin 4 receptor deficiency: Schwiertz et al. (2010) reported that obesity is linked to the composition of human microbiota and the production of SCFAs, providing an additional source of energy for the body. In addition to being energy sources, SCFAs control colonic gene expression by inhibiting the enzyme HDAC and metabolic regulation by signaling through G-protein–coupled receptors, such as GPR41 and GPR43 (Tremaroli and Bäckhed 2012). Significant elevation of colonic Gpr41 and Gpr43 mRNAs further indicated activation of bacterial fermentation by TCDF.