INS and obesity due to melanocortin 4 receptor deficiency: Increased mTOR activation in skeletal muscle of humans with obesity in the fasted state may result from effects of an obesity-associated insulin resistance on increasing the plasma amino acids (Felig et al., 1969; Adams, 2011), and given the role of increased concentrations of plasma amino acids (and insulin) in activating mTOR (Tremblay et al., 2005).