Carnitine aids the transport of fats into the machinery of muscle cells (mitochondria), where it's burned for fuel. It has been shown in reseach to improve fat loss during exercise and low-carb dieting. Additionally, it enhances recovery and increases the number of testosterone receptors in muscle cells. Carnitine is also as a potent NO booster.
Take 1,000-3,000 mg in the form of L-carnitine, acetyl-L-carnitine, L-carnitine-L-tartrate or glycine propionyl-L-carnitine (GPLC) in the morning and with evening meals. Some take their dose pre and post-workout.