What Are the Best Peptides for Muscle Growth? Revolutionary decellularized Alstroemeria stem based nerve conduit integrated with GelMA and controlled IGF 1 LR3 release for enhanced rat sciatic nerve regeneration ScienceDirect 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 Overexpression of Igf2 derived Mir483 inhibits Igf1 expression and leads to developmental growth restriction and metabolic dysfunction in mice ScienceDirect