# Practical Approach to Designing and Implementing a Recommendation System for Healthy Challenges
###### Abstract  
Background: The COVID-19 pandemic has worsened sedentary lifestyles and unhealthy eating habits. It is crucial to promote proper training and healthy habits for all to prevent physical and cognitive decline. This should be a priority in health and education initiatives to reduce deaths and noncommunicable diseases. Guidelines for nutrition, physical activity, and sleep emphasize the importance of healthy habits. The goal is to develop a recommendation tool with a diverse range of challenges to positively impact users' health. Methods: The process involves thoroughly obtaining precise user profiles through widely used questionnaires such as the Short-Form Health survey, the short Healthy Eating Index, and the Oviedo Sleep Questionnaire, and characterizing the challenges. Then, an algorithm will be developed to identify and prioritize the most suitable challenges for each user, ensuring personalized recommendations. Results: A pool of 30 health challenges was created based on reputable recommendations and experts. The system underwent validation by external experts and received positive user feedback, confirming its effectiveness. The panel of experts and users validated the personalized and reliable recommendations. Conclusions: Simple lifestyle interventions have shown promise for primary prevention in developed countries. A prototype system has been created to evaluate the individual weakness of users and suggest evidence-based lifestyle challenges. The system conducts a thorough health assessment and ensures feasibility for preventive purposes. Validation has proven the system's effectiveness in recommending health-enhancing challenges with no adverse effects. The design of the model supports the seamless addition of new challenges by eventual third parties, ensuring interoperability and scalability. challenge; health promotion; healthy habits; physical activity; recommender algorithm; healthy lifestyle +
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Considering the general increase in life expectancy worldwide (according to the WHO, it has grown by five years since the year 2000 [11]), it becomes evident that promoting proper training and adopting healthy lifestyle habits among all segments of the population is crucial for preventing physical and cognitive decline. Incalculating these habits should be a primary objective of health and education initiatives in the present era. From the perspective of primary prevention, defined by [PERSON] [12] as \"the measures taken to prevent the occurrence of a disease\", or by the WHO [13] as \"measures aimed at avoiding the occurrence of a disease or health problem by controlling causal and predisposing factors\", it is reasonable to assert that a significant number of deaths and illnesses can be prevented by adopting a healthy lifestyle [14; 15; 16]. Unhealthy dietary habits and physical inactivity significantly increase the risk of developing NCDs [17; 18]. NCDs account for 74% of global annual deaths, making up seven of the top ten causes of death worldwide [19]. As such, promoting healthy lifestyle habits, encompassing nutrition, physical activity (PA), and mental well-being, is a matter of paramount importance for countries in the Organization for Economic Cooperation and Development (OECD). Low adherence to nutritional, PA, and behavioral plans remains a significant obstacle to establishing these habits. In these domains, which encompass healthy lifestyle habits including nutrition, PA, mental health, and sleep quality, well-established guidelines exist. These guidelines include healthy eating guidelines (HEG) from organizations such as the Food and Agriculture Organization (FAO) [20], US Department of Health and Human Services [21], and the WHO [18; 22; 23]. Additionally, there are guidelines on PA practice and its benefits for physical and mental health supported by research [14; 15]. Furthermore, the National Sleep Foundation (NSF) provides sleeping guidelines (SG) [24; 25].