Evaluating the Effectiveness of the Motivational Interviewing–Based Wellness Coaching for Kids and Families (WC4K) Program in Pediatric Obesity Care: Protocol for a Cluster Randomized Pragmatic Trial

Background The increasing prevalence of severe obesity among youth and the early onset of comorbidities highlight the urgent need for effective solutions to support behavior and lifestyle changes. Motivational interviewing (MI), a client-centered counseling technique, has shown promise in improving obesity-related outcomes and is now recommended by the American Academy of Pediatrics as a key component of behavioral interventions for children with overweight and obesity. Objective This study aimed to describe the design and baseline characteristics of the Wellness Coaching for Kids and Families (WC4K) program, an MI-based behavioral health intervention integrated into pediatric primary care within a large integrated health care system. This trial aims to inform broader implementation strategies for other health care systems. Methods We are conducting a cluster randomized pragmatic trial across 50 pediatric clinics within Kaiser Permanente Southern California. Clinics were randomized to either the intervention arm (n=24, 48.00%) or the usual care arm (n=26, 52.00%), targeting children aged between 3 and 8 years with overweight or obesity. Pediatricians in intervention clinics received MI training and referred families to centralized health coaches for tailored telephone counseling. Key behavioral targets include increased fruit and vegetable intake, reduced consumption of sugar-sweetened beverages, increased physical activity, and reduced screen time. The primary outcome is a change in BMI-for-age, measured as relative distance from the median using electronic medical record data. Secondary outcomes include parent-reported behavior change indicators. Results The source population includes 150,482 children from clinics serving predominantly low-income and racial and ethnic minority populations. After randomization, intervention and control clinics were similar in demographics (standardized mean differences <0.2 for key variables), with 77,481 (51.49%) children in the WC4K intervention clinics and 73,001 (48.51%) children in the control clinics. In the total clinic population, 36.58% (55,052/150,482) of the children were overweight or with obesity. Enrollment started in fall 2022, study results are expected in spring 2027. Conclusions If the trial results indicate success in reducing BMI and improving health behaviors, WC4K may offer a scalable and sustainable model for integrating behavioral health coaching into pediatric primary care. By leveraging MI-trained pediatricians and centralized health coaching, WC4K has the potential to facilitate meaningful lifestyle changes in children with overweight or obesity. Trial Registration ClinicalTrials.gov NCT05143697; https://clinicaltrials.gov/study/NCT05143697 International Registered Report Identifier (IRRID) DERR1-10.2196/78792