Understanding consumption of animal- and plant-based protein sources in the Netherlands: a stakeholder-driven causal loop diagram

Current consumption of animal-based protein sources is environmentally unsustainable and poses risks to human health, animal welfare, and food security. Policymakers in many countries seek to reduce the consumption of animal-based protein sources. However, this transition is affected by many factors, and it remains unclear how they interact and what their potential is for stimulating systemic change. This study synthesized stakeholders' perspectives on factors driving the consumption of animal- and plant-based protein sources into a Causal Loop Diagram (CLD), visualising factors and their cause-and-effect relationships. Three Group Model Building sessions with 28 stakeholders (consumers, researchers, industry representatives, policymakers, interest group members) from the Netherlands informed the CLD. The Action Scales Model was used to categorize factors into system levels (events, structures, goals, and beliefs), providing insights into their potential for systemic change. The resulting CLD reveals the complexity of protein consumption across five interconnected subsystems: 1) Individual Aspects, 2) Social Interactions & Culture, 3) Physical Food Environment, 4) Food Industry & Natural Food Environment, and 5) Politics & Regulation. The high interconnectivity indicates isolated interventions are unlikely to be sufficient for systemic change, as feedback mechanisms may counteract or neutralize their effects. Addressing multiple elements across the system is thus essential to accelerate the protein transition. This study provides a foundation for understanding the system dynamics shaping consumption of animal- and plant-based protein sources. However, further research is needed to incorporate quantitative weighting, determine the relative importance of mechanisms and identify leverage points for systemic change to guide policy development.