Understanding the Benefits and Uses of Carnitine in Health and Fitness Fitness Health 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. 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 NKF KDOQI Guidelines NFH L Carnitine Tartrate SAP 90C