BACKGROUND Psychological factors have been reported to have influence on the eating habits of patients with diabetes. However, previous studies have used questionnaires to investigate the association, and thus include recall bias. To overcome this disadvantage, ecological momentary assessment (EMA) can be used to record subjective symptoms and behavior in subjects' daily lives. Therefore, the aim of the present study was to investigate the influence of preceding psychological factors on calorie intake using computerized EMA for 6 months. METHODS The participants were nine outpatients with type 2 diabetes, aged 34-72. They were instructed to use a personal digital assistant as an electronic diary for 6 months to record subjective symptoms, such as psychological stress, anxiety, and depressive mood, and the food and drink that they consumed. The association between a preceding psychological factor and calorie intake within 5 hours was investigated using multilevel modeling. RESULTS Preceding psychological stress was positively associated with calorie intake from snacks. Preceding psychological stress, anxiety, and depressive mood were negatively associated with calorie intake from regular meals. CONCLUSIONS Preceding psychological factors influence the calorie intake of patients with type 2 diabetes. Understanding the role of these factors will be useful for developing psychological interventions to prevent overeating. BACKGROUND The trial registration number: UMIN000002992. Date of registration: 2010/01/07.