L Carnitine has become one of our top 5 sellers the last few years and when you review the research, you can see why. L carnitine is a supplement probably more well known if How to Lose Weight With PCOS 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. L Carnitine has become one of the most commonly asked about supplements over the past 18 months and I can see why when looking at all the research that has come out about it over the last 2ish years.,