**Background:** Front-of-package nutrition labelling (FOPNL) is a policy tool to encourage healthier food choices and reformulation. Grading schemes such as Nutri-Score (NS) and Health Star Rating (HSR) are two market-implemented interpretive FOPNLs, but no prior study had compared them across an entire national food supply. This study aimed to evaluate alignment between NS and HSR and identify where they diverge, using a large branded foods database and sales data.
**Methods:** The study used cross-sectional data from the Slovenian Composition and Labelling Information System (CLAS, 2020), which included 28,028 pre-packed foods from seven major retailers. After exclusions (categories not covered by NS/HSR, missing mandatory nutrition data, products requiring preparation, and energy calculation errors >±20%), 17,226 products from 12 main categories and 53 subcategories remained. Missing data for fibre, fruit/vegetable/nut/legume content (% FVNL), and calcium were imputed using established methods. NS grades were calculated per French Public Health Agency instructions (4 profiling categories: General, Beverages, Added fats, Cheeses). HSR grades were calculated per Australian Government criteria (6 profiling categories). For comparison, HSR's ten grades were collapsed into five to match NS's five grades. Healthiness cut-offs were A/B for NS and ≥3.5 stars for HSR. Agreement was assessed using % agreement, Cohen's Kappa, and Spearman correlation. Sale-weighting used 12-month national sales data (2020) available for 62% (n = 10,724) of products.
**Key Results:** NS graded 22% of the food supply as healthy (A or B), while HSR graded 33% as healthy (≥3.5 stars). Overall agreement was strong (70%, κ = 0.62) with very strong correlation (rho = 0.87). Agreement was perfect (100%) for Waters, Frozen fruit, and Frozen vegetables. The highest alignment was in Beverages and Bread and bakery products. The lowest alignment was in Cheese and processed cheese (8% agreement, κ = 0.01, rho = 0.38), Cream (14%, κ = 0.03, rho = 0.26), Cooking oils (27%, κ = 0.11, rho = 0.40), Margarine (27%, κ = 0.13, rho = 0.72), and Unprocessed chilled fish (54%, κ = 0.30, rho = 0.55). For Cooking oils, NS favoured olive and walnut oil (grade C) over grapeseed, flaxseed, and sunflower oil (grades D/E), while HSR graded most oils 3.5–4 stars. For Cheese and processed cheese, HSR distributed products across all grades with 63% classified as healthy (≥3.5 stars), while NS graded 82% as D. Sale-weighting increased overall agreement from 70% to 81%, but deepened differences in some categories (e.g., Cooking oils agreement dropped from 27% to 6%).
**Clinical Implications:** The choice of nutrient profiling model substantially affects which products are classified as healthy, with NS being stricter overall (11% fewer products classified as healthy versus HSR). Divergences in Cheese and Cooking oils reflect different public health priorities—NS incorporates specific oil types (olive, walnut, rapeseed) based on French nutritional recommendations, while HSR does not. HSR's extended scoring scales for protein and fibre lead to higher ratings for nuts, seeds, and some processed meats, which may conflict with dietary guidelines recommending limited consumption of these products. Sale-weighting revealed that market-leading products (e.g., sunflower oil) can amplify disagreements between schemes. These findings underscore the need for international harmonization of nutrient profiling to ensure consistent messaging for consumers and to support regulatory implementation of FOPNL across different countries.