3-Aminoisobutyric acid (also known as β-aminoisobutyric acid or BAIBA) is a product formed by the catabolism of thymine. During exercise, the increase of PGC-1α protein triggers the secretion of BAIBA from exercising muscles to blood (concentration 2 to 3 μM in human serum). When BAIBA reaches the white fat tissue, it activates the expression of thermogenic genes via PPARα receptors, resulting in a browning of white fat cells. One of the consequences of the BAIBA activity is the increase of the background metabolism of the BAIBA target cells.