The effectiveness of a brief online dietary feedback intervention on reducing adults’ discretionary choice intake

Abstract This study evaluated the effectiveness of a brief online dietary feedback intervention designed to reduce adults’ intake of discretionary choices by incorporating tailored nutrition message frames and behaviour change techniques (BCTs). A total of 3,453 adults enrolled online, and 1,441 completed the follow-up surveys. Participants were randomised to receive either two emails with tailored nutrition message frames and enhanced behavioural support (delivered through nine embedded BCTs, such as goal setting and action planning), or two emails with generic nutrition messages without additional support. The primary outcome was daily servings of discretionary choices (energy-dense, nutrient-poor foods and beverages), and secondary outcomes included predictors of intake reduction. No significant difference in discretionary choice intake was observed between the groups (3.2 ± 0.13 vs 3.1 ± 0.12 servings, p = 0.49). However, lower baseline diet quality was a significant predictor of a one serving or more reduction in discretionary choice intake (OR 1.57, 95% CI [1.47, 1.68], p < 0.001). These findings suggest that tailoring message framing based on intention, even when combined with established BCTs, may not enhance dietary outcomes in motivated populations. Future interventions may be more effective if they focus on less motivated individuals with lower baseline diet quality and explore alternative approaches to message tailoring.