We intraperitoneally (i.p.)injected leptin receptor-deficient (db/db) obesity model mice with phosphate-buffered saline (PBS) or 0.5 μg of recombinant IL-33 (rIL-33) to activate ILC2s for 5 consecutive days. The gene discussed is LEPR; the disease is obesity due to melanocortin 4 receptor deficiency.