JMIR Publications

ABSTRACT

Background:

Smartphone applications (apps), fitness trackers, and online social networks have shown promise in weight management and physical activity interventions. However, knowledge gaps remain regarding which are the most effective and engaging interventions, and what intervention features are preferred by their users.

Objective:

This 6-month study pilot tested a social networking mobile app connected to wireless weight and activity tracking devices to evaluate effects on body mass index (BMI), weight, and physical activity levels in users from different BMI categories. Another aim was to assess user perspectives on the intervention, particularly on social comparison and automated self-monitoring and feedback.

Methods:

This was a mixed-methods study involving a one-arm, pre-post quasi-experimental pilot with post-intervention interviews and focus groups. Healthy young adults used a social networking mobile app intervention integrated with wireless tracking devices (a weight scale and a physical activity tracker) for 6 months. Quantitative results were analysed separately for two groups—underweight-normal BMI and overweight-obese—using t-tests, Wilcoxon sum rank, Wilcoxon-signed rank, and Chi-square tests. Weekly BMI change of participants was explored using linear mixed effects analysis. Interviews and focus groups were analysed inductively using thematic analysis.

Results:

Fifty-five participants were recruited (mean age of 23.6 years; 28 women) and 45 returned for the final session (retention rate=81.8%). There were no differences in BMI change from baseline to post-intervention (6 months) overall and between the two BMI groups. However, at 4 weeks participants had lowered their BMI by 0.34 Kg/m2 (P<0.001), with a loss of 0.86 Kg/m2 in the overweight-obese group (P=0.01). Participants in the overweight-obese group used the app significantly less compared to individuals in the underweight-normal BMI group, as they mentioned negative feelings and demotivation from social comparison, particularly from upward comparison with fitter people. Participants in the underweight-normal BMI group were more avid users of the app’s self-monitoring and feedback (P=0.02) and social features (P=0.04) compared to participants in the overweight-obese group, and significantly increased their daily step count over the 6-month study duration by an average of 2292 steps (confidence interval 898 to 3370; P<0.001). Most participants mentioned a desire for a more personalised intervention.

Conclusions:

Our study showed different intervention effects on participants from higher and lower BMI groups. Participants in the overweight-obese group did not sustain the short-term decrease in their BMI and mentioned negative emotions from app use. Participants in the underweight-normal BMI group used the app more frequently and significantly increased their daily step count. These differences, compounded by distinct perspectives regarding the intervention, highlight the importance of intervention personalisation. Future research should explore the use of personalised features to help overcome personal barriers and better match individual preferences and needs.