L Carnitine is Underrated. New Meta Review Reminds Us Why. Let's cut through the marketing noise and look at the actual science of fat loss. A lot of supplements make big claims, but L Carnitine is heavily backed by research for its The effect of (L)carnitine on weight loss in adults: a systematic review and metaanalysis of randomized controlled trials Pooyandjoo 2016 Obesity Reviews Wiley Online Library Losing weight with L carnitine supplements. Yes or no? 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