#584: EAT-Lancet: Does the Planetary Health Diet Improve Human Health?

Introduction to this Episode

How should we think about diets that claim to optimise both human and planetary health? Can a single “reference diet” really balance the complex trade-offs between nutrition adequacy, chronic disease prevention, and environmental sustainability?

These questions have gained renewed attention with the release of the 2025 update to the EAT-Lancet Planetary Health Diet. The original 2019 report proposed a mostly plant-based dietary pattern designed to improve population health while staying within planetary boundaries. But since then, new data have emerged—on nutrient requirements, disease risk, and environmental modelling—that complicate many of the original assumptions.

What does the updated evidence actually say about the health impacts of eating in line with this framework? How have the environmental projections changed? And what do these evolving targets mean for individuals, policymakers, and researchers trying to translate broad sustainability goals into practical dietary guidance?

These are some of the questions explored in this episode of Sigma Nutrition, which examines the 2025 EAT-Lancet update, its scientific foundations, and what it reveals about the intersection of nutrition, health, and planetary sustainability.

EAT-Lancet Report and Planetary Health Diet

“Transformation to healthy diets by 2050 will require substantial dietary shifts: global consumption of fruits, vegetables, nuts, and legumes will need to double, while intake of foods such as red meat and sugar must be reduced by more than 50%. A diet rich in plant-based foods and lower in animal-source foods confers both improved health and environmental benefits.” – Prof. Walter Willett MD

Useful Terminology for this Episode

• EAT-Lancet Commission: The research consortium (involving The Lancet journal and the EAT Foundation) that produced the planetary health diet guidelines. The commission brings together nutrition scientists, environmental experts, and policy makers to create evidence-based recommendations for diets that are both healthy for people and sustainable for the planet.
• Planetary Health Diet (PHD): A diet pattern recommended by the EAT-Lancet Commission that emphasizes plant-based foods (fruits, vegetables, whole grains, legumes, nuts, unsaturated fats) and includes only modest amounts of animal products. It is designed to promote human health (by reducing chronic disease risk) while also minimizing environmental impact.
• Prospective Cohort: A type of observational epidemiological study that follows a group of people over time, collecting data on their diet and health outcomes.
• Dietary Pattern Score (or Index): A numerical score that quantifies how closely an individualʼs diet matches a specific dietary pattern or guideline. For example, the “Planetary Health Diet Index” assigns points based on intake of the 14 food groups in the PHD. Higher scores indicate greater adherence to the pattern.
• Nutrient Adequacy: Refers to whether a diet provides sufficient amounts of essential nutrients (vitamins, minerals, protein, etc.) to meet the populationʼs nutritional requirements.
• Food System Transformation: A broad term for changes in how food is produced, distributed, and consumed on a societal level. In this context, shifting to the planetary health diet implies a transformation of the global food system (e.g. more sustainable farming of plant foods, reduced livestock production) rather than just individual changes in eating habits.