In contrast, we noticed obesity-related upregulation of Slc27a2 and Acaa1b (Table S2A), which are engaged in long-chain fatty acid activation and thiolysis, respectively, implying an increase in long-chain fatty acid oxidation; consequently, the level of C12 acylcarnitine, an intermediate metabolite of long-chain fatty acid oxidation, increased in the colonic epithelium of young obese mice (Figure S1C). The gene discussed is SLC27A2; the disease is obesity due to melanocortin 4 receptor deficiency.