There are benefits over and above improved appearance. First, recent medical findings tell us that fat loss is critical to health. The key predictor for cardiac wellness and longevity is related not to weight, but to lean body mass; ie to the absence of fat. Thus an overweight person with too high a percentage of fat carries much higher morbidity and mortality risks than does a person of the same weight with less fat and more muscle. Medical science is consequently influencing the diet/exercise market to shift from a weight loss to a fat loss paradigm. The dietician's new credo, "Healthy at any weight", focuses on the conversion of fat into muscle, as opposed to the reduction of weight per se. 'Lean', the marketing catchword of this decade, no longer means underweight; it means minimal fat in conjunction with firm, defined musculature.