Second, knockout of IκB kinase ɛ (IKKɛ) which is upregulated by NF-kB was shown to promote thermogenesis and prevent HFD induced obesity in mice68; accordingly, fewer cells utilizing NF-kB signaling after CL and cold exposure may also promote thermogenesis. Here, NFKB1 is linked to obesity due to melanocortin 4 receptor deficiency.