The present invention relates to the unexpected discovery that a combination of effective amounts of carnitine (in any form, as described in further detail herein) and conjugated linoleic acid (CLA) administered to a patient in need thereof exhibits synergistic activity in treating obesity by reducing fat mass and overall weight as well as one or more of hyperlipidemia, hypercholesterolemia, diabetes (both diabetes mellitus I and II), metabolic syndrome (syndrome X), kidiney failure and high blood pressure, where those conditions exist.