When Should You Take L Carnitine? MuscleTech Men's Why Use L Carnitine Convenient liquid shot for faster delivery into the blood stream Added Pantothenic Acid which works directly with carnitine to help convert macronutrients into energy. It's also great L Carnitine for Fat Loss: Does It Actually Burn Fat? (Canada) 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.