JMIR Publications

ABSTRACT

Background:

Young adults are more likely to use self-managed dietary reporting applications. However, scant research has examined the user experience of different measurement approaches for mobile dietary reporting applications when dealing with a wide variety of food shapes and container sizes that reflect everyday life conditions.

Objective:

Field user experience testing was conducted under actual meal conditions to assess the accuracy, efficiency, the subjective reaction of three food portion measurement methods embedded in a developed mobile app. Each of the three methods featured a unique user interaction design. Key-in-based aid (KBA), commonly used in many current apps, relies on the user’s ability to key-in volumes or weights. Photo-based aid (PBA) extends traditional assessment methods, allowing users to scroll, observe and select a reduced-size image from a set of options. Gesture-based aid (GBA) is a new experimental approach in which the user makes finger movements on the screen to roughly describe food portion boundaries accompanied by a background reference.

Methods:

A group of 124 young adults aged 19-26 were recruited for a head-to-head randomized comparison, and divided into three equal groups: a KBA (n=42) control group, and PBA (n=41) and GBA (n=41) experimental groups. Three meals (breakfast, lunch, and dinner) were served in a university cafeteria. Participants were provided with twenty-five dishes and beverages for selection with a variety of food shapes and containers that reflect everyday life conditions. The accuracy and time spent on realistic interaction during food portion estimation and the subjective reaction of each aid were recorded and analyzed.

Results:

Among the twenty-five food dishes and drinks provided in the cafeteria, participants in the KBA trial provided the highest accuracy in terms of hash brown weight (p=0.004), and also outperformed PBA or GBA for many soft drinks in cups. PBA had the best results for a cylindrical hot dog (p<0.001), irregular shaped pork chop (p<0.001), and green tea beverage (660ml, p<0.001). GBA outperformed PBA for most drinks and KBA for some vegetables. The GBA group spent significantly more time assessing food items than the KBA and PBA groups. For each aid, the overall subjective reaction based on the score of the System Usability Scale (SUS) was not significantly different. Moreover, the score of KBA and PBA surpassed the benchmark.

Conclusions:

Experimental results show that each aid had some distinguishing advantages. In terms of user acceptance, participants considered all three aids to be usable. Furthermore, users’ subjective opinions regarding measurement accuracy contradicted empirical findings. Future work will consider the use of each aid based on food or container shape, and integrate the various advantages of the three different aids for better results. Our findings on the use of portion size aids are based on realistic and diverse food items, providing a useful reference for future application development and improvement of an effective, evidence-based feature, and acceptable feature in mHealth applications. Clinical Trial: http://www.isrctn.com/ISRCTN36710750