IGF-1 LR3 (Insulin-Like Growth Factor-1 Long Arginine 3) is a synthetic, modified form of insulin-like growth factor-1. Because IGF-1 LR3 does not bind well to IGF-1 binding proteins, it remains active up to 120 times longer than standard IGF-1, resulting in an improved half-life and increased biological activity. IGF-1 LR3 enhances cell division and growth, boosts fat metabolism, and increases muscle repair and hypertrophy by inhibiting myostatin. Recent research suggests that IGF-1 LR3 may also be useful in improving lactation among mothers with young offspring.