INS and obesity due to melanocortin 4 receptor deficiency: Obesity has emerged as a pressing global endocrine-related health challenge, disrupting key hormonal axes (e.g., the insulin–glucose regulatory axis and the leptin–ghrelin axis), and is strongly associated with type 2 diabetes mellitus (T2DM), dyslipidemia, thyroid dysfunction, and polycystic ovary syndrome (PCOS)—conditions that are central to clinical endocrinology (1, 2).