Abstract: A monitoring apparatus that includes a sensor device and an I/O device in communication with the sensor device that generates derived data using the data from the sensor device. The derived data cannot be directly detected by the associated sensors. Alternatively, an apparatus that includes a wearable sensor device and an I/O device in communication with the sensor device that includes means for displaying information and a dial for entering information. Alternatively, an apparatus for tracking caloric consumption and caloric expenditure data that includes a sensor device and an I/O device in communication with the sensor device. The sensor device includes a processor programmed to generate data relating to caloric expenditure from sensor data. Alternatively, an apparatus for tracking caloric information for an individual that utilizes a plurality of classification identifiers for classifying meals consumed by the individual, each of the classification identifiers having a corresponding caloric amount.