Mice with combined deficiency of FABP4 and FABP5 (Fabp4−/−Fabp5−/−) on a high-fat diet or in a genetic obesity model exhibit remarkably improved insulin resistance and protection against type 2 diabetes and fatty liver disease more than did FABP4- or FABP5-deficient mice [18, 19]. The gene discussed is FABP4; the disease is obesity due to melanocortin 4 receptor deficiency.