The Role of l Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation Fast&Up L Carnitine 3000mg Effervescent Tablets L Carnitine 3500 Metabolic Nutrition How L Carnitine Helps with Fat Metabolism L Carnitine is not a magic fat burner It won't melt fat, build muscle, or replace hard work. The only thing it burns is your money Stick to the basics 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.