Skeletal muscle activities are inversely related to obesity because obesity accelerates muscle atrophy and decelerates muscle strength via regulating the activities of TNF-α, Ang II, AGEs, Myostatin, exogenous GC, IL-6, I/IGF, vitamin D, Ca2+, estrogen, testosterone and leptin. Here, IGF1 is linked to obesity due to melanocortin 4 receptor deficiency.