Can digital support groups promote healthy eating? A randomized trial in daily life

Abstract

Background: Social support has shown promise to regulate health behaviour. However, most research has focused on support by close others. We investigated whether support provided in digital groups can promote healthy eating. Furthermore, we tested the temporal development of intervention effects, and two mediating processes: Received social support and action control (i.e., awareness of standards, self-monitoring, and self-regulatory effort). Methods: In this 2 x 2 trial (support vs. information-only x increasing fruit & vegetable consumption vs. decreasing unhealthy snack consumption), 208 adults were randomly allocated to intervention arms. Participants completed a 13-day daily diary on food consumption, support, and action control. During days 4-10, support participants were instructed to support their eating goal achievement in smartphone-based chat groups. Two independent raters coded the chat messages using the Social Support Behaviour Code. The data was analysed using multilevel modelling. Findings: Social support participants showed a significant gradual increase in healthy eating over time. Compared to controls, support participants ate 1.4 servings of fruits and vegetables more (CI95: 0.3, 2.6) or 0.8 unhealthy snacks less (CI95: -1.4, -0.2) on the last intervention day. Of the 1144 chat messages, the most frequent support types were attentiveness (18.7%), informational (14.2%), and esteem support (12.8%). Intervention effects were mediated by action control. Discussion: This study demonstrated that digital support groups successfully promote healthy eating. The results further provided interesting insights into the temporal dynamics of behaviour change, and emphasized the importance of investigating such dynamics for building a theory of behaviour change in daily life.