Carnitine: the claims and why it may not work L Carnitine isn't magic but it can be a powerful tool when your training and nutrition are already dialed in Here's why I like it Supports fat metabolism L Carnitine helps L Carnitine Benefits, Uses, Dosage, Foods, Side Effects Dr. Axe Does L Carnitine Work For Fat Loss? L carnitine is a naturally occurring amino acid structure that is made in the human brain, liver, and kidneys. L carnitine plays a critical role in energy production, as it converts fat into energy.