Increased accumulation of fatty acids in tissues as seen in obesity leads serine/threonine phosphorylation of IRS proteins, resulting in a decreased signaling through reduced tyrosine phosphorylation and increased proteasomal degradation of IRS‐1 causing depression in the expression (Shulman, 2000; White, 2002). This evidence concerns the gene IARS1 and obesity due to melanocortin 4 receptor deficiency.