Common Phentermine Drug Interactions to Avoid GoodRx L Carnitine is one of the most hyped weight loss supplements online but here's what most won't tell you: Your body naturally produces L Carnitine using amino acids l, and a healthy person usually Two ingredients. One powerful transformation. Meet the Phentermine + L Carnitine combothe ultimate support for effective weight management. Here's how it works: Phentermine = curbs appetite & reduces cravings L Carnitine = Frontline L Carnitine Fit Factory Supplements Two ingredients. One powerful transformation. Meet the Phentermine + L Carnitine combothe ultimate support for effective weight management. Here's how it works: Phentermine = curbs appetite & reduces cravings L Carnitine =