While fat substitution in foods is big business, massive replacement of natural fats with fat substitutes would not be easy or necessarily wise, according to a UC Davis food chemist. Despite the negative attention they receive in this weight-conscious society, fats are actually remarkable compounds necessary in judicious amounts for nutritional health, according to J. Bruce German, an authority on lipids, which are fat or fat-like substances in plants and animals. He notes that as societies with low-fat diets develop economically, fattier foods are invariably added to the diet. Such an innate preference for fatty foods makes evolutionary sense, because fats contain twice the caloric energy of proteins or carbohydrates, he says. Fat-rich foods may also contain essential fatty acids and help break down certain vitamins. Likewise, fats provide desirable flavor, structure and creamy texture for foods. German spoke earlier this year at a meeting of the American Chemical Society.