This study also showed that, in the HFD-Con group, where obesity was induced, the expression of proteins related to mitochondrial fission, Drp1 and Fis1, increased, whereas the expression of proteins related to mitochondrial fusion, Mfn1, Mfn2, and Opa1, decreased. The gene discussed is FIS1; the disease is obesity due to melanocortin 4 receptor deficiency.