The loss of Acot7 [41], Acot11/Them1 [24], Acot13/Them2 [42], and Acot15/Them5 [36] result in phenotypes ranging from increased neurodegeneration to altered susceptibility to high-fat diet induced obesity, fatty liver, and insulin resistance through unknown mechanisms that unexpectedly altered whole body metabolism. This evidence concerns the gene ACOT13 and obesity due to melanocortin 4 receptor deficiency.