I. INTRODUCTION
AKEY factor in maintaining healthy life is balancing
energy intake and expenditure. Abnormalities in this
balance can lead to diseases, such as obesity, anorexia, and
other eating disorders, which may furthermore deteriorate into
chronic diseases if not seriously treated [1]. A crucial step to
solve the problems is to continuously measure daily calorie
balance [2]. There are many off-the-shelf solutions to measure
calorie expenditure, such as Fitbit, Philips DirectLife, etc.
However, continuously and non-invasively monitoring calorie
intake remains a challenge.