L Carnitine L Tartrate Capsules Get Fit & Tone Up L Carnitine 5000 L carnitine helps transport fatty acids into your cells' mitochondria, where they can be used for energy. That's why it's often marketed for fat loss and energy support. Common use: People usually take When should I take L carnitine? (L Carnitine) Should I use L Carnitine on rest days or just before workouts? How Much L Carnitine Per Day: Expert Guide The Science of Good Health