A method for non-invasive monitoring of human food intake behavior and long-term dietary protocol has been developed by the sole use of chewing and swallowing sound sensors. A novel sensor system has been built containing an in-ear microphone and a reference microphone integrated in a hearing aid case in order to record chewing and swallowing sounds in the ear canal and environmental noise, respectively. Using manual labeled records of the food intake sounds of 40 participants we developed an algorithm to detect food intake activity in sound data. Comparison between sounds from both microphones enables the discrimination between internal and external sounds.