A system for determining resting metabolic rate (RMR) based primarily on oxygen consumption is described. The system consists of an enclosed, sealed chamber within which the patient/subject sits or reclines. The rate of volumetric oxygen change in the system is then monitored to determine the subjects' oxygen consumption rate. The rate of the subjects volumetric oxygen consumption is then converted by the system, using the widely accepted Weir formulation, to calculate RMR. The system is capable of making this calculation in under 10 minutes, making the measurement highly convenient for the subject. The system contains a display mounted on or within the chamber to both serve as a user interface, as well as to serve as a platform for informative programming such as advertisements for weight loss and diet centers and nutrition related products. The system contains a money dispensing system in order that users can pay for the metabolic test. Finally, the system is also capable of obtaining two ancillary parameters, percent body fat and respiratory quotient.