INS and obesity due to melanocortin 4 receptor deficiency: Intriguingly, Postn deficiency has been reported to attenuate LPS-/HFD-induced AT fibrosis and to improve IR; thus, the lower Postn levels found herein may contribute to healthy hyperplastic AT expansion and maintain insulin sensitivity during obesity [83,84], as we observed in the LFABP−/− mouse model.