Several obesity-associated molecular factors and signaling pathways such as adipokine production, alterations in the insulin-like growth factor 1 (IGF-1) signaling pathway, excessive steroidal sex hormone production, chronic low-grade inflammation, oxidative stress, and gut dysbiosis were identified to influence tumor cell biology, but the underlying mechanisms have not been fully elucidated (Parekh et al., 2012; Park et al., 2014a; Avgerinos et al., 2019). The gene discussed is IGF1; the disease is obesity due to melanocortin 4 receptor deficiency.