Early research into L carnitine was often cited as underwhelming, showing negligible changes in muscle carnitine content and fat loss outcomes. However, these findings may have been limited by a short study window Carnitine: the claims and why it may not work L carnitine is an amino acid derivative that plays a crucial role in the body's energy production processes. As an injectable supplement, L carnitine has been employed to support various health conditions, including heart Systemic regulation of L carnitine in nutritional metabolism in zebrafish, Danio rerio Scientific Reports