Electronic systems, devices and methods are provided to accurately record and analyze food intake and physical activity in a subject. A device is provided to be placed on a subject which records video using at least two video cameras positioned to record stereoscopic image pair, as well as other physiological and/or environmental data including, for example, oxygen saturation, heart rate, and environmental factors such as physical location, temperature, and humidity. Video data is analyzed along with other data obtained by the device to determine food consumption and/or physical activity of the subject, much of which is accomplished by automated computer-implemented processes.