IGF 1 LR3 Dosage Guide: Benefits, Timing, and Results i313 IGF 1 LR3 does not promote growth in late gestation growth restricted fetal sheep American Journal of Physiology Endocrinology and Metabolism American Physiological Society IGF 1LR3 Advanced Anabolic Signaling & Muscle Growth 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 The Definitive Guide