Basal metabolism in women with obesity and anorexia nervosa.

The results of measurements of basal metabolic rate in patients with obesity and anorexia nervosa have suggested that the basal metabolic activity of cell mass is altered in these diseases. It has been shown repeatedly that basal metabolism, expressed as oxygen consumption per unit of time, is high in obesity and low in anorexia nervosa. When the oxygen consumption per unit of time is referred to the usual reference variable, the body surface area, the values remain low for anorexia nervosa but become normal for obese patients. Since it was earlier thought that body-weight increase in obesity depended on a gain in pure fat, i.e. the metabolically inactive depot substance in fat tissue, it was concluded that obesity is accompanied by hypermetabolism. The adequacy of the body surface area as a reference variable for the expression of the basal metabolism has been questioned repeatedly. This question became of current interest during the last decade with the introduction of in vivo ‘chemical dissection’ (Edelman, Olney, James, Brooks & Moore, 1952) and the measurement of the density of the body (Behnke, Osserman & Welham, 1953) which permitted the determination of different parameters for the metabolically active part of the body in living human subjects, cell mass or lean body mass. Different authors have suggested that lean body mass or cell mass a priori should be considered as more adequate reference variables for basal metabolism than surface area. Studies of body composition in patients with anorexia nervosa demonstrated the loss of large quantities of cell mass. Furthermore, such studies showed that, contrary to previous opinion, there occurs in obesity an increase not only in metabolically inactive depot fat but also in cell mass. These latter observations suggested that the changes in basal metabolism in patients with obesity and anorexia nervosa might be ‘physiological’, due to quantitative changes in cell mass, and that they are not due to hyperor hypo-metabolism. In the present work basal metabolism and body composition were estimated in patients with obesity and anorexia nervosa as well as in a group of healthy women. The relations between basal metabolism and different parameters of cell mass were compared between the different groups of subjects. The results showed that the basal metabolic activity did not differ in these three groups, since the basal metabolism was of the same magnitude when the cell mass was used as a basis of comparison.