Empowering healthy lifestyle behaviour through personalised intervention portfolios using a healthy lifestyle recommender system to prevent and control obesity in older adults: pilot study protocols from the HealthyW8 project.

INTRODUCTION: Obesity prevalence has increased globally, imposing a significant burden on individuals and societies. Innovative solutions are, therefore, essential to mitigate its impact. METHODS AND ANALYSIS: This protocol outlines the framework of seven independent European pilot studies conducted in Bulgaria, Germany, Luxembourg and Spain, under the EU-Horizon HealthyW8 project. These studies aim to evaluate as primary outcomes feasibility, usage patterns (adherence) and user satisfaction of the Healthy Lifestyle Recommender System (HLRS), a personalised digital tool designed to promote healthy lifestyles through tailored physical activity and meal recommendations, considering emotional aspects. The seven pilot trials will collectively include 240 (around 30 participants/trial) older adults (≥65 years) with overweight (body mass index (BMI) 25.0-29.9 kg/m EXPECTED OUTCOMES: It is hypothesised that participants will use the HLRS consistently enough to assess its feasibility and impact. The findings will contribute to planning and executing long-term trials focused on health outcomes and enhance understanding of the multimodal nature of obesity risk and its comorbidities. This protocol facilitates comparisons across studies in diverse cultural and contextual settings, offering insights into how personal and environmental factors influence the implementation and effectiveness of the HLRS. ETHICS AND DISSEMINATION: Ethical approval has been obtained in each country independently. Dissemination efforts will prioritise high-impact journal publications. TRIAL REGISTRATION NUMBER: NCT07011368.