In addition to measurement differences, it has been suggested that mitochondrial respiratory function is not related to insulin sensitivity, and that the joint observation of changes in mitochondrial content and/or respiration and insulin resistance is coincidental or linked by a common factor (s), which might include physical inactivity, obesity, or reduced skeletal muscle blood flow [92,93]. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.