Acetate levels were significantly increased in serum of HFD Ptcd1+/- mice but not in NCD-fed Ptcd1+/- mice compared to controls (Figure 2B), consistent with the previously reported protective role of acetate in diet induced obesity [22–26] and the HFD protective effects in Ptcd1+/- mice. This evidence concerns the gene PTCD1 and obesity due to melanocortin 4 receptor deficiency.