IGF-1 LR3 (insulin-like growth factor-1 long arginine 3) is a synthetic, modified construct of insulin-like growth factor-1. Because IGF-1 LR3 does not bind to IGF-1 binding proteins very well, it remains active up to 120 times longer than standard IGF-1. This results in improved half-life for the peptide and thus increased 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.