JMIR Publications

ABSTRACT

Background:

Diet and physical activity (PA) have a major impact on physical as well as mental health. However, there is a lack of effective strategies to sustain health-protective behaviors. Studying micro-temporal, within-person processes underlying eating behavior and PA in daily life is an important next step in the improvement of interventional approaches. Yet, a tool which allows capturing these processes in daily life is so far missing.

Objective:

The APPetite-mobile-app was developed for the ecological momentary assessment (EMA) of micro-temporal, within-person processes of complex dietary behavior, objectively recorded PA, and related factors. This study evaluated the feasibility and usability of the APPetite-mobile-app as well as the validity of the incorporated APPetite-food record.

Methods:

The APPetite-mobile-app captures dietary intake event-contingent through a prospective food record, PA continuously through accelerometers, and related factors (eg, stress) signal-contingent through 8 prompts per day. Empirical data on feasibility (n=157) and usability (n=84) as well as validity (n=44) were collected within the Eat2beNICE-APPetite-study. Feasibility and usability were examined in healthy participants and psychiatric patients. Relative validity of the APPetite-food record was assessed in a subgroup of healthy participants using a cross-over-counterbalanced design. The reference method was a 24-hour recall. Additionally, energy intake was compared to total energy expenditure (TEE) estimated from accelerometry.

Results:

Good feasibility with compliance rates above 80% for the prompts and the accelerometer as well as reasonable average response and recording durations (prompt: 2.04 minutes, food record per day: 17.66 minutes) and latencies (prompts: 3.16 minutes, food record: 58.35 minutes) was found. Usability was rated moderate with a score of 61.9/100 in the System Usability Scale. The evaluation of validity identified large differences in energy and macronutrients intake between the two methods on the group as well as individual level. The APPetite-food record captured higher dietary intakes, indicating a lower level of underreporting compared to the 24-hour recall. Energy intake was assessed fairly accurate by the APPetite-food record on the group level on 2 of 3 days when compared to TEE. The comparison with mean TEE (2417.8 kcal) showed that the 24-hour recall (1909.2 kcal) underestimated habitual energy intake to a larger degree than the APPetite-food record (2146.4 kcal).

Conclusions:

The APPetite-mobile-app is a promising tool to capture micro-temporal, within-person processes of diet, PA, and related factors in real time or near real time and is, to the best of our knowledge, the first of its kind. First evidence supports good feasibility and moderate usability of the APPetite-mobile-app as well as validity of the APPetite-food record. Future findings in the context of micro-temporal, within-person processes of diet, PA and related factors will build the foundation for the development of personalized lifestyle modification interventions, such as just in-time adaptive interventions.