Abstract: A stand-alone, fully integrated self-contained wearable metabolic analyzer for metabolic rate and respiratory quotient measurement. It includes a device body, disposable mask, and headgear. The device body comprises multiple different miniaturized modules, including a colorimetric sensing module, flow module, control circuit, power module, environmental sensors, wireless module, communication module, memory module, signal processing module, and display module. A disposable sensor chip, coated with chemical sensing probes, is utilized in the colorimetric sensing module for breath O2 and CO2 detection. A Venturi tube and pressure sensor-based flow module measures breath flow rate. The self-contained wearable metabolic analyzer derives physiological parameters including resting energy expenditure (REE), respiratory quotient (RQ), oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE), breath frequency (BF), and tidal volume (TV) from the measurement.