Utilising implementation intentions to promote healthy eating in adolescents

Objectives: This study evaluated a school-based behaviour change intervention for adolescents to address unhealthy eating habits that may otherwise “track” into adulthood. Design: A behaviour change intervention was conducted utilising implementation intention formation (or if-then planning) for adolescents to achieve two healthy eating goals: (1) including fruit and vegetable in each daily meal, and (2) replacing unhealthy snacks with healthy choices. Methods: Participants (N = 107) aged between 16 and 18 years were randomised to intervention, active control and passive control conditions. Intervention participants formed implementation intentions for achieving the healthy eating goals; participants in the active control condition completed health-related tasks; and passive control participants read health information. Eating habits and intentions were measured at baseline and 5-month follow-up. Results: Findings showed that the intervention was not effective in achieving the healthy eating goals. Conclusions: Our findings give some indication that implementation intentions alone may not be a powerful enough means of changing eating behaviour in this age group. We reflect in detail upon the elements of the intervention that may have prevented its success in changing behaviour, for example, its failure to raise motivation, and the target of potentially unsuitable self-regulatory goals. We also discuss our findings, for example, on forming multiple plans and the role of intentions, within the context of current literature.