In 2012, Laurentino et al made a study between 3 groups: a low resistance group, a low resistance group, and blood flow restriction, and high-intensity resistance training. The researchers were looking at the blood levels of myostatin, strength, and muscle cross sectional area growth. As you may have anticipated, myostatin decreased in the light resistance with the BFR group and the high resistance group.
Myostatin is a protein that inhibits muscle growth. In nature, you find this in animals such as the Belgian Blue Cattle. This is a massive cow with huge muscles. Researchers noticed this changed after they removed this protein from a mouse. They expected the mouse to die but instead the mouse got bigger, more muscle with less fat.