How IGF 1 and MGF drive muscle growth after training Gabriel Alizaidy, MD, MS posted on the topic LinkedIn IGF 1 LR3 (Insulin like Growth Factor 1 Long R3) is often called the "Holy Grail" of muscle building peptides because of its potent anabolic effects. In a Med Spa context, it is typically sought out IGF 1 DES for Bodybuilding: Dosage, Benefits & Side Effects Emerging Anabolic and Regenerative Peptides in Athletic Body Re composition and Bodybuilding: Mechanisms of Action, Dosing Strategies, and Evidence Review