Though IL-33 maintains ILC2s function in steady state, it may display complex functions in ILC2s during obesity, which leads to the decreased fraction of ILC2s in VAT The deficiency of ILC2s induces an insufficient production of IL-5, leading to decreased numbers of eosinophils in VAT and decreased secretion of IL-4. The gene discussed is IL33; the disease is obesity due to melanocortin 4 receptor deficiency.