JMIR Publications

ABSTRACT

Background:

Nutrition apps offer scalable opportunities to support dietary behavior change and prevent chronic diseases. Their success depends on sustained user engagement, which is essential but difficult to achieve. Despite growing efforts to enhance engagement, it remains unclear which strategies are used and how engagement is measured.

Objective:

This review summarizes the current engagement approaches and metrics employed in research trials targeting adult populations.

Methods:

We conducted a systematic search of PubMed, Scopus, Cochrane and Web of Science for relevant studies from January 1, 2013, to June 2024. The research combined findings from 59 studies, including randomized controlled trials, observational trials and mixed-methods studies using apps to improve dietary behaviors.

Results:

The majority of these apps focused on adults with overweight and obesity and underwent (non-) randomized controlled trials, with varying durations and sample sizes. Engagement was typically measured by frequency of specific function use and frequency of app usage right, followed by retention rate. The two most common engagement strategies reported in studies were push notifications (49%) and behavioral theory elements (41%). The lack of consistent definitions of user engagement limited comparison across studies and made it difficult to interpret the use and impact of engagement strategies. The majority of research examined short- to medium-term engagement patterns although this limited the understanding of long-term behavior change.

Conclusions:

Our findings suggest that adaptive user-centered design together with standardized engagement metrics should be implemented to enhance nutrition app effectiveness.