We applied an innovative agent-based modeling (ABM) approach to investigate how and to what extent spillover effects occur beyond dietary interventions.

We developed an agent-based-model (ABM) in NetLogo to simulate the dietary practices of the Dutch adult population during lunch and dinner, representing participants in the Dutch National Food Consumption Survey.

The model assessed spillover effects beyond a hypothetical workplace canteen intervention targeting increased plant-based protein consumption during lunch. Direct effects were defined as the percentage of non-vegetarian employees consuming a vegetarian lunch. Spillover effects were indicated by the percentage of plant-based protein consumed at dinner, influenced by dietary identity, habituation, social networks, and eating location. Scenarios with varying direct effect sizes were simulated to compare plant-based protein consumption at dinner.

Simulations demonstrated a positive spillover effect at the population level, with plant-based protein consumption at dinner increasing over three years compared to baseline (no intervention). At direct intervention effect sizes up to 0.5, there was a linear increase in plant-based protein consumption at dinner (from 23.0% [95%CI 22.9–23.2] at baseline to 32.3% [95%CI 31.8–32.8]). Spillover effects plateaued beyond an effect size of 0.5, with no significant further increases observed.

Our application of ABM revealed that positive spillover effects of dietary interventions from workplace to home can be achieved. Despite challenges, ABM might complement other approaches for studying spillover effects and supporting dietary behavior change towards more sustainable diets.