L Carnitine: Benefits, Side Effects & Dosage BulkSupplements.com 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 Benefits, Uses, Dosage, Foods, Side Effects Dr. Axe L Carnitine Benefits: A Complete Research Based Guide If you are like a lot of people, you may have never heard of carnitine but this important nutrient is critical for our body's ability to optimally burn fat required for energy.