Effectiveness and Feasibility of Self-Monitoring for Weight Management in Individuals With Mental Disorders Using Digital Intervention: Protocol for a Stepped-Wedge Cluster Randomized Trial (“SWIM” Study)

Background: Individuals with schizophrenia or bipolar disorder face a significantly elevated risk of obesity, primarily due to weight gain associated with psychiatric medications and lifestyle factors. While digital self-monitoring tools offer scalable solutions, their application remains underexplored in psychiatric populations. To address these gaps, this type 1 hybrid effectiveness-implementation study investigates the preliminary effectiveness and implementation feasibility of a mobile health-assisted weight management intervention for patients with severe mental illness. Objective: This study aims to evaluate the preliminary effectiveness and implementation feasibility of a mobile health-assisted weight management intervention for patients with severe mental illness transitioning from inpatient care to community-based recovery. Methods: This single-center, open-cohort stepped-wedge cluster randomized trial with a 2-month step duration will recruit 204 patients from 6 clinical units. Clusters are randomized into 2 waves, with staggered transitions to a digital intervention, including smart scales, health apps, and biweekly educational modules, over a 6-month observation period. The design evaluates the intervention across the transition from inpatient care to community-based recovery. The primary outcome is the proportion of participants achieving ≥5% weight loss at month 6. Implementation feasibility is assessed through device technical success and intervention adherence (defined as ≥50% completion of weekly weigh-ins and daily dietary logs). Results: Participant data collection began in May 2023 and was completed by June 2025 with a total of 204 participants. The publication of key findings and results is anticipated in late 2026. Conclusions: This protocol describes a pragmatic, technology-supported intervention designed to address metabolic side effects in a tertiary psychiatric setting. By bridging the gap between acute hospitalization and community recovery, this hybrid stepped-wedge cluster randomized trial provides a crucial framework for integrating digital metabolic monitoring into routine clinical workflows for vulnerable populations.