This entry is summarised, not reproduced: the full text is not ours to host.
DatBTrue wrote a series of mechanism essays for Synthetek product pages in 2009. This one, on injectable L-carnitine, argues that carnitine availability limits the transport of fatty acids into mitochondria, and that the effect depends on glycogen and insulin status. It is a commercial piece written to support a product, and it should be read with that in mind: the physiology is cited, the conclusion is the one the seller needs.
Source: Synthetek Industries, 2009. Rights held by the manufacturer. The entry stays in the index so the recovered set remains complete.