LEP and obesity due to melanocortin 4 receptor deficiency: The characteristic profile of soluble factors in obesity and aging, such as decreased adiponectin, elevated levels of C-reactive protein (CRP), leptin, tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6), could lead to progressive loss of muscle mass and an increase in fat mass [14, 16, 37–40].