Although the role of excess body weight in leukemia etiopathogenesis is not fully elucidated, and the main pathways linking obesity adiposopathy to leukemia are complicated and comprise BMAT; hormones including insulin and the insulin-like growth factor system as well as sex hormones; pro-inflammatory cytokines and growth factors, such as IL-6 and TNF-α; adipocytokines, such as adiponectin, leptin, resistin, and visfatin; dyslipidemia and lipid signaling; chronic low-grade inflammation and oxidative stress; and other emerging mechanisms. This evidence concerns the gene LEP and leukemia.