Carnitine and acetyl L carnitine Neuroneeds L CARNITINE increases muscle mass, reduces fat mass. Bangkok Hospital Headquarter What Is L Carnitine? L Carnitine Benefits, Dosage & When To take? MYPROTEIN 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