A metabolic physical activity monitor measures metabolic analyte data using one or more wearable analyte sensors. The sensors may be incorporated into a self-contained device or communicatively coupled to an external computing device like a smartphone or computer or both. Sensors may be mounted on any body surface including the skin, under the eyelid or in the mouth. Metabolic Analyte biomarker data may include electrolytes, various metabolites, pCO2 and pO2 in sweat, saliva and tears. Sensor data are used to calculate specific biomarker values, including calorie expenditure. Sensor readings are taken for at least two points during a period of physical activity. Changes in readings are used to determine total and rate of caloric expenditure for the time period. Readings may also be used to evaluate a users wellness. By using measured changes in relative values complex calibration procedures can be eliminated, while reproducibility is much more easily achieved.
