A wearable device or system for monitoring food consumption can include a wrist-worn or finger-worn device which is worn by a person, a motion sensor on the wrist-worn or finger-worn device, eyewear which is worn by the person, and a camera on the eyewear which is activated to record food images when analysis of data from the motion sensor detects that the person is eating. This device can be used alone or as part of a closed-loop glucose level management system.