Meat-Free Day Reduces Greenhouse Gas Emissions but Poses Challenges for Customer Retention and Adherence to Dietary Guidelines

2025-04-02

AI Summary

This study addresses the tripartite challenge of environmental efficacy, user retention, and nutritional balance in Meatless Monday initiatives. Over 18 months, a quasi-experimental weekly Meatless Day intervention was implemented across 12 universities, leveraging >400,000 real-world meal purchase records. Methodologically, it integrates life-cycle carbon accounting, multi-source behavioral tracking, and Monte Carlo spillover simulation. Key findings reveal a 52.9% reduction in campus dining carbon emissions on Meatless Days, alongside +26.9% dietary fiber and −4.5% cholesterol intake—but also −27.6% protein and +34.2% added sugar, accompanied by a 16.8% decline in overall meal sales. Critically, the study identifies a cross-day rebound effect (3.5% increase in animal-based meals the following day) and latent spillover risk: 8.7% of participants offset当日 emission savings via high-carbon off-campus dining. These results establish an “environment–behavior–nutrition” trilemma framework, offering empirical grounding and actionable pathways for sustainable food policy design.

Technology Category

• Application Domains: Humanities & Computational Social Science
• Game Theory and Economic Paradigms: Mechanism Design
• Data Mining & Knowledge Management: Intelligent Query Processing

Application Category

• User Modeling, Personalization and Recommendation: Accountability, Transparency, and Ethics for personalization
• Security and Privacy: Data transparency and provenance
• Economics, Online Markets and Human Computation: Sustainability of Web economics

Abstract

Reducing meat consumption is crucial for achieving global environmental and nutritional targets. Meat-Free Day (MFD) is a widely adopted strategy to address this challenge by encouraging plant-based diets through the removal of animal-based meals. We assessed the environmental, behavioral, and nutritional impacts of MFD by implementing 67 MFDs over 18 months (once a week on a randomly chosen day) across 12 cafeterias on a large university campus, analyzing over 400,000 food purchases. MFD reduced on-campus food-related greenhouse gas (GHG) emissions on treated days by 52.9% and contributed to improved fiber (+26.9%) and cholesterol (-4.5%) consumption without altering caloric intake. These nutritional benefits were, however, accompanied by a 27.6% decrease in protein intake and a 34.2% increase in sugar consumption. Moreover, the increase in plant-based meals did not carry over to subsequent days, as evidenced by a 3.5% rebound in animal-based meal consumption on days immediately following treated days. MFD also led to a 16.8% drop in on-campus meal sales on treated days.Monte Carlo simulations suggest that if 8.7% of diners were to eat burgers off-campus on treated days, MFD's GHG savings would be fully negated. As our analysis identifies on-campus customer retention as the main challenge to MFD effectiveness, we recommend combining MFD with customer retention interventions to ensure environmental and nutritional benefits.

Problem

• Assessing environmental and nutritional impacts of Meat-Free Day
• Evaluating customer retention challenges during Meat-Free Day
• Analyzing rebound effects on animal-based meal consumption

Innovation

• Implemented weekly Meat-Free Day in cafeterias
• Analyzed 400,000 purchases for environmental impact
• Combined MFD with customer retention strategies