Social Networks for Improving Healthy Weight Loss Behaviors for Overweight and Obese Adults: A Randomized Clinical Trial of the Social Pounds off Digitally (Social Pod) Mobile App

Document Type




To test the efficacy of a weight loss mobile app based on recommender systems and developed by experts in health promotion and computer science to target social support and self-monitoring of diet, physical activity (PA), and weight (Social POD app), compared to a commercially available diet and PA tracking app (standard).

Materials and methods

Overweight adults [N = 51] were recruited and randomly assigned to either the experimental group [n = 26; theory-based podcasts (TBP) + Social POD app] or the comparison group (n = 25; TBP + standard app). The Social POD app issued notifications to encourage users to self-monitor and send theory-based messages to support users who had not self-monitored in the previous 48 h. Independent samples t-test were used to examine group differences in kilograms lost and change in BMI. Analysis of covariance was used to analyze secondary outcomes while controlling for baseline values.


Participant attrition was 12% (n = 3 experimental and n = 3 comparison). Experimental group participants lost significantly more weight (−5.3 kg, CI: −7.5, −3.0) than comparison group (−2.23 kg, CI: −3.6, −1.0; d = 0.8, r = 0.4, p = 0.02) and had a greater reduction in BMI (p = 0.02). While there were significant differences in positive outcome expectations between groups (p = 0.04) other secondary outcomes (e.g., caloric intake and social support) were not significant.


Use of the Social POD app resulted in significantly greater weight loss than use of a commercially available tracking app. This mobile health intervention has the potential to be widely disseminated to reduce the risk of chronic disease associated with overweight and obesity.