Assessing Behavioral and Environmental Facets of Obesity Unobtrusively Utilizing Digital Tools: Introducing the BETTER4U Indicators.

Understanding obesity involves evaluating numerous contributing factors. Collecting the necessary data for this can impose a significant burden on both research participants during clinical studies and real-life deployments of digital tools aiding obesity management. The BETTER4U project (European Union's Horizon Europe, Grant Agreement ID 101080117) introduces 36 behavioral and 9 living environment indicators designed to unobtrusively and efficiently capture daily life through passive monitoring using market-available smartphones and smartwatches while accounting for environmental confounders. This concise set, intended for dietitians, physical activity experts, and healthcare professionals as a standard for assessing obesity-related behavior, summarizes the behavioral and environmental profile of a person with obesity/overweight. We present the selected indicators, their selection and implementation methodology and the high-level plan for their verification, describing their conceptual foundations and technical realization. These indicators can be deployed in a modular framework: by transforming raw sensor data into structured, interpretable measures they provide a scalable foundation for long-term monitoring of obesogenic behaviors, individual assessment, and evaluation of interventions targeting physical activity, diet, stress, and sleep. The indicators are intended for an expert-facing dashboard within the BETTER4U Intervention Platform, a participant-side interface within the BETTER4U application, and as input to the BETTER4U AI-based causal model, supporting relationship modeling between behavior, environment, and obesity outcomes to inform personalized interventions. This work lays the basis for data-driven validation of these indicators following the "BETTER4ALL Pilot Study" (ClinicalTrials.gov ID: NCT07120802), ahead of their use in the BETTER4U RCT among individuals with obesity/overweight.