Obesity-related accumulation of BCAA in plasma has been reported to interfere with the insulin signaling via activation of the mammalian target of rapamycin (mTOR) pathway, precisely the complex mTOR/p70S6K [86,87,88,89], with leucine as the most potent mTOR activator [90]. This evidence concerns the gene MTOR and obesity due to melanocortin 4 receptor deficiency.