L Carnitine 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 tartrate supplementation in the fight against infectious disease In terms of fat burning ability.. L Carnitine may not be the brightest star in the sky, but it has another effect that few people actually know about. This content is for educational