EASE-CF: dietitian-led weight-loss intervention for adults with cystic fibrosis and excess weight: protocol for a feasibility randomised controlled trial

Introduction Advances in cystic fibrosis (CF) care have coincided with an increasing prevalence of excess body weight in this population, which may contribute to cardiometabolic and respiratory morbidity. However, evidence to guide intentional weight loss in this population is limited and safety concerns remain due to the established positive association between body weight and lung function. Delivering weight-loss interventions in CF is likely to be complex because of CF-specific factors, high treatment burden and embedded dietary advice focused on high-energy, high-fat diets for weight gain. To inform the design of a future definitive randomised controlled trial (RCT), we plan to test the feasibility, acceptability and safety of a dietitian supported weight-loss intervention compared with routine care. Methods and analysis This multicentre feasibility RCT with an embedded qualitative study, will recruit 30 adults with CF and body mass index ≥27 kg/m 2 from four UK specialist centres. Participants will be randomised 2:1 to the EASE-CF intervention or routine dietetic consultations, with follow-up over 24 weeks. The remotely delivered, theory-informed intervention combines structured dietary energy restriction, meal replacements and behavioural support from specialist CF dietitians. Participants randomised to routine care will continue to receive standard CF dietetic input. The primary objective is to assess the feasibility of progression to a definitive RCT based on pre-specified criteria on recruitment, engagement, adherence, retention and safety. Assessment of intervention acceptability and fidelity will be explored through process measures and qualitative interviews with participants and healthcare professionals. Exploratory outcomes include changes in body weight and composition, lung function, quality of life, physical function and metabolic markers. Ethics and dissemination Ethical approval has been granted by the National Research Ethics Service South Central B Research Ethics Committee (ref: 25/SC/0323). Findings will be disseminated through stakeholder engagement, conference presentations and publication in open-access, peer-reviewed journals. Trial registration number NCT17298282 .