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 Frontiers Association between fatigue, peripheral serotonin, and L carnitine in hypothyroidism and in chronic fatigue syndrome Carnitine: the claims and why it may not work Does L carnitine produce a clinically meaningful effect within four hours? Is L Carnitine safe for athletes at doses up to 6000 mg day? Consensus