What should we ask patients living with obesity every week? Towards a phenotype-informed framework for continuous digital patient-reported data in obesity care

Obesity is now formally recognised as a chronic, relapsing, multifactorial disease, and highly effective medications have transformed its management, while exposing how little health systems know about what happens to patients between consultations. Care pathways are saturating; in routine care most patients discontinue pharmacotherapy within a year; and the data used to understand and evaluate obesity care remain episodic, clinic-bound and weight-centred. The International Consortium for Health Outcomes Measurement (ICHOM) has taken the essential first step by defining, through international consensus, a standardised outcome set for adults living with obesity. This paper proposes a complementary layer, distinct from the outcome set's evaluative mandate: a continuous measurement framework. It describes a short weekly collection of patient-reported data, complemented by clinician-reported and passively captured data, modulated by each patient's phenotype and treatment phase. The framework serves three functions: understanding each patient's obesity, evaluating the care provided, and supporting treatment management. Its structure, a minimal common core plus standardised phenotype-triggered modules, preserves the comparability of the aggregate dataset. Its design principles answer the constraints of a population exposed to stigma, the inequity risks of digital-only administration, and the known attrition of self-administered tools. The elements are in place: consensus outcome sets, validated phenotypes and instruments, feasibility evidence. What is missing is their assembly into an open, shared standard, and that assembly demands competencies no single actor holds alone: clinical expertise and access to patients, measurement science, and command of the technology, of remote care delivery and of the regulatory frameworks that make continuous collection real. This paper is an invitation to co-construct it.