Boosting Healthiness Exposure in Category-constrained Meal Recommendation Using Nutritional Standards

Food computing, as a newly emerging topic, is closely linked to human life through computational methodologies. Meal recommendation, a food-related study about human health, aims to provide users a meal with courses constrained from specific categories (e.g., appetizers, main dishes) that can be enjoyed as a service. Historical interaction data, as important user information, is often used by existing models to learn user preferences. However, if user’s preferences favor less healthy meals, the model will follow that preference and make similar recommendations, potentially negatively impacting the user’s long-term health. This emphasizes the necessity for health-oriented and responsible meal recommendation systems. In this paper, we propose a healthiness-aware and category-wise meal recommendation model called CateRec, which boosts healthiness exposure by using nutritional standards as knowledge to guide the model training. Two fundamental questions are raised and answered: 1) How to evaluate the healthiness of meals? Two well-known nutritional standards from the World Health Organisation and the United Kingdom Food Standards Agency are used to calculate the healthiness score of the meal. 2) How to health-orientedly guide the model training? We construct category-wise personalization partial rankings and category-wise healthiness partial rankings, and theoretically analyze that they meet the necessary properties and assumptions required to be trained by the maximum posterior estimator under Bayesian probability. The data analysis confirms the existence of user preferences leaning towards less healthy meals in two public datasets. A comprehensive experiment demonstrates that our CateRec effectively boosts healthiness exposure in terms of mean healthiness score and ranking exposure, while being comparable to the state-of-the-art model in terms of recommendation accuracy.