JMIR Publications

ABSTRACT

Background:

A substantial proportion of adults with obesity do not meet global physical activity (PA) recommendations, even though PA is known to provide health benefits beyond weight loss. Most online PA-promoting interventions (a) are developed and tested outside clinical obesity care, (b) embed generic PA guidance within diet‑focused programs, and (c) inadequately address obesity‑specific PA barriers. To address these gaps, we developed Confident Moves (CM), an obesity‑tailored, theory‑driven online PA-promoting intervention, and established its feasibility within an obesity care center in the United States of America in a 2025 feasibility trial.

Objective:

This randomized controlled trial (RCT) will evaluate the efficacy of CM on device‑measured PA and whole person health compared with standard obesity care alone.

Methods:

This study is a 16‑week, prospective, individually randomized, two‑arm, fully remote efficacy RCT. A total of 348 patients from two obesity care centers within a single state in the United States of America will be recruited and randomized to CM plus standard obesity care or standard obesity care alone. Participant recruitment began in July 2026 and is ongoing as of protocol submission. Eligibility screening, informed consent, intervention delivery, and survey data collection will be conducted online via the CM website, with device‑measured PA assessed via mailed accelerometers. Data will be collected across three waves over up to 16 weeks. Participants assigned to the CM group will receive 4 weeks of access to the intervention between wave 1 and wave 2. Device‑measured PA will be assessed at wave 1 and wave 3 using wrist‑worn accelerometers mailed to participants. Self‑reported PA, self‑efficacy, PA outcome expectations, and whole person health will be assessed via psychometrically valid scales. Primary hypotheses will examine the effects of CM on device‑measured PA and whole person health, whereas secondary hypotheses will focus on self‑efficacy, including its response to CM and its associations with these outcomes. Data will be analyzed under an intent‑to‑treat framework, with complier average causal effect models applied as appropriate based on engagement.

Conclusions:

This protocol describes a fully powered efficacy RCT evaluating CM, an online, obesity‑tailored PA-promoting intervention integrated within clinical obesity care. Using a rigorous remote design, device‑based PA measurement, and prespecified analyses, the trial will generate evidence to inform the readiness of CM for future effectiveness and pragmatic trials.