INS and obesity due to melanocortin 4 receptor deficiency: Conversely, metabolically healthy obesity is characterized by beneficial adipose tissue expansion driven by hyperplasia, where new, smaller, and more insulin-sensitive adipocytes derived from adipocyte precursor cells (APCs), which consist of adipose stem and progenitor cells (ASPCs) committed to adipocyte lineage differentiation [9,11,[15], [16], [17], [18]].