Carnitine, just like other supplements, is meant to supplement hard training and a healthy diet. Yes, there is evidence that carnitine can help improve fat oxidation, which has the body use fat for fuel instead of other energy substrates (22), but it isn’t a miracle product on its own.  Carnitine can give you some extra help and may push your fat loss further than without it, but you still have to do the hard work of exercising and eating right.