INS and obesity due to melanocortin 4 receptor deficiency: BCAA levels in adolescents with obesity are sex‐dependent, and reduction in ‘BMI% exceeding the 95th percentile’ during lifestyle intervention is associated modestly with increases in BCAA catabolism: BCAA levels decline and the urea cycle amino acids rise in parallel with reduction in ‘BMI% above the 95th percentile’ and an increase in insulin sensitivity.