In 2016, Boulenouar and colleagues showed that NK cells could regulate adipose tissue macrophages via their ability to kill inflammatory macrophages, but with the onset of obesity, NK cells lost their ability to kill macrophages and increased their production of IFN-γ which promoted the recruitment of inflammatory macrophages, promoting obesity related metabolic defects (233). This evidence concerns the gene IFNG and obesity due to melanocortin 4 receptor deficiency.