Supplement of the week: L Carnitine! This one doesn't just boost fat metabolismit can also improve recovery, endurance, and even brain function. If you're serious about performance and longevity, this might be L Carnitine L CARNITINE increases muscle mass, reduces fat mass. Bangkok Hospital Headquarter Should I use L Carnitine on rest days or just before workouts? 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