An improvement in glucose tolerance in the absence of a reduction in fat mass has also been shown by Matsuzaka et al. in mice deficient in Elovl6, the gene that encodes the elongase responsible for the conversion of palmitate to stearate: obesity-induced insulin resistance is ameliorated through modulation of hepatic metabolism, without a concurrent reduction in obesity [20]. Here, ELOVL6 is linked to obesity due to melanocortin 4 receptor deficiency.