INS and obesity due to melanocortin 4 receptor deficiency: Indeed, it has been previously demonstrated that individualized Fatmax training may significantly increase muscle oxidative capacity, as well as fat oxidation rates during exercise and insulin sensitivity in obese individuals [19, 43], highlighting its clinical relevance in the treatment of obesity [37] and the importance of correctly assessing Fatmax as a function of measured V ̇O2peak [44].