In persons with metabolically unhealthy obesity, excessive adiposity leads to adipocyte hyperplasia, which is mainly driven by the recruitment of adipogenic progenitors and growth factors, such as insulin-like growth factor-1 (IGF-1), tumor necrosis factor-α (TNF-α), angiotensin II (Ang II), and macrophage colony stimulating factor (M-CSF). The gene discussed is IGF1; the disease is obesity due to melanocortin 4 receptor deficiency.