Hypoxia activates the transcription factor hypoxia-inducible factor-1α (HIF-1α), which induces expression of various target genes; deletion of HIF-1α in adipocytes partially protects mice from HFD-induced obesity and insulin resistance compared with similarly fed wild-type controls [32, 33]. This evidence concerns the gene HIF1A and obesity due to melanocortin 4 receptor deficiency.