L-Carnitine LiquiFast Description: Natural Sport L-Carnitine LiquiFast supplement is a great tasting L-Carnitine supplement. This supplement is intended to provide nutritive support for individuals engaged in exercise, bodybuilding, weight training and athletic sports. L-Carnitine primary role in the body is helping to transport fatty acids into the mitochondria, where the fatty acids are used as a source for producing energy. Your muscles need energy to work properly.