Acute L Carnitine Supplementation Does Not Improve CrossFit Performance: A Randomized, Double Blind, Placebo Controlled Crossover Study 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 L Carnitine is Underrated. New Meta Review Reminds Us Why. Effect of L carnitine on quality of life in covert hepatic encephalopathy: a randomized, double blind, placebo controlled study