SLC2A4 and Insulin resistance: Branched-chain amino acids (BCAA, leucine, valine) are linked to insulin resistance via GLUT4 [43] and the accumulation of BCAA and BCAA degradation products found in our metabolomic study [19] could be an early sign of insulin resistance as further indicated by the significantly increased plasma levels of glucose (p = 0.005), fructosamine (p < 0.001), insulin (p = 0.03), and HOMA-IR (p = 0.02) in both groups from week 4 to week 20.