Previous work has shown that there is no demonstrable dependence of obesity upon food intake or caloric balance.1 Neither can it be proved that any consistent relation exists between constitutional obesity and basal metabolism.2 It has been shown, however, that these people show a lower specific dynamic action of protein following a high protein intake than normal and thin people.3 The work here reported was done in conjunction with our investigations on basal metabolism and specific dynamic action of foods. While the figures of this work, based, as they are, on the urinary nitrogen and the nonprotein respiratory quotient, may not be considered as absolutely exact, attention is called to the fact that their relative value is unimpaired because conditions were so well controlled. Each subject served for at least three tests, which were conducted by the same person and under the same conditions except for the type of meal