Dietary indexes based on the EAT-Lancet recommendations: a narrative review

Abstract Background The publication of the EAT-Lancet Commission in 2019 has motivated the development of numerous dietary indexes to evaluate how different populations adhere to its proposed dietary guidelines aimed at promoting both human and planetary health. However, the lack of methodological harmonization among these indexes limits their comparability and applicability in population-level assessments. This narrative review aims to synthesize the existing EAT-Lancet-based indexes, identify limitations, and propose criteria to develop a new index. Methods We conducted a non-systematic narrative search to identify dietary indexes based on the EAT-Lancet recommendations and published up to April 24, 2025. The information was synthesized in a comparative table, including scoring structure, the food groups considered, and the identified limitations. Results We identified thirteen original indexes and three systematic reviews evaluating eleven of these indexes. Analysis of the indexes show important common limitations: the use of the same score for each category, not considering the EAT-Lancet recommended ranges, grouping of food items with very different environmental impacts (such as beef and pork), penalizing vegetarian diets, and not penalizing unhealthy foods such as alcohol, cocoa, and coffee. A new index is proposed which weights every food group according to four environmental dimensions, gives maximum scores within the recommended ranges, separates cheese from the rest of the dairy, allows for interchangeability between protein and fat sources and it penalizes unhealthy foods and total caloric deviations. Conclusions This review confirms the methodological heterogeneity across thirteen dietary indexes based on the EAT-Lancet recommendations. We propose the creation of a new standardized index to address the limitations of previous indexes and foster greater consistency in future studies, and better applicability of planetary principles across diverse populations. Key messages • A standardized method to measure the dietary environmental impact is needed to support effective strategies that benefit both public and planetary health. • This review highlights major methodological differences among the existing EAT-Lancet-based indexes and the need for harmonization to ensure comparability across diverse populations.