Effectiveness of an Online Programme to Tackle Individual's Meat Intake through SElf-regulation (OPTIMISE): A randomised controlled trial.

Purpose: A reduction in meat intake is recommended to meet health and environmental sustainability goals. This study aimed to evaluate the effectiveness of an online self-regulation intervention to reduce meat consumption.

Methods: One hundred and fifty one adult meat eaters were randomised 1:1 to a multi-component self-regulation intervention or an information-only control. The study lasted 9 weeks (1-week self-monitoring; 4-week active intervention; and 4-week maintenance phase). The intervention included goal-setting, self-monitoring, action-planning, and health and environmental feedback. Meat intake was estimated through daily questionnaires in weeks 1, 5 and 9. The primary outcome was change in meat consumption from baseline to five weeks. Secondary outcomes included change from baseline to nine weeks and change in red and processed meat intake. We used linear regression models to assess the effectiveness of all the above outcomes.

Results: Across the whole sample, meat intake was 226 g/day at baseline, 118 g/day at five weeks, and 114 g/day at nine weeks. At five weeks, the intervention led to a 40 g/day (95%CI - 11.6,- 67.5, P = 0.006) reduction in meat intake, including a 35 g/day (95%CI - 7.7, - 61.7, P = 0.012) reduction in red and processed meat, relative to control. There were no significant differences in meat reduction after the four-week maintenance phase (- 12 g/day intervention vs control, 95% CI 19.1, - 43.4, P = 0.443). Participants said the intervention was informative and eye-opening.

Conclusion: The intervention was popular among participants and helped achieve initial reductions in meat intake, but the longer-term reductions did not exceed control.

Trial Registration: ClinicalTrials.gov NCT04961216, 14th July 2021, retrospectively registered.