IGF 1 LR3 The Muscle Building Peptide Everyone's Talking About IGF 1 LR3 is one of the most powerful performance peptides used for muscle growth, recovery, and fat loss. It's a modified version IGF 1: Miracle Hormone or Health Hazard? Diet vs Disease IGF 1 LR3 does not promote growth in late gestation growth restricted fetal sheep American Journal of Physiology Endocrinology and Metabolism American Physiological Society Growth Hormone and Insulin like Growth Factor I: Novel Insights into the Male Reproductive Health IntechOpen