In a model of mouse obesity caused by high-fat diet (HFD), the accumulation of adipose tissue macrophages (ATMs) within the white adipose tissue (WAT) involves remodeling of the enlarged WAT and induction of insulin resistance via secreting proinflammatory mediators IL-1β and TNF5, 6. The gene discussed is IL1B; the disease is obesity due to melanocortin 4 receptor deficiency.