More recently, β-aminoisobutyric acid (BAIBA), a non-protein amino acid secreted by skeletal muscles upon regular exercise via peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)-dependent mechanism, has been discovered as a novel endogenous protective myokine regulating adipose tissue browning, improving insulin sensitivity and protecting against a high-fat diet-induced obesity [22,23,24]. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.