A cluster-randomized controlled trial of a family-based psychosocial intervention to prevent childhood obesity from preschool ages: the PRESAFALIN study protocol

Abstract Background: Childhood obesity is a major global concern, and Spain's high obesity rates highlight the urgent need for effective and innovative interventions in early age. The PRESAFALIN study aims to promote parental competence, self-efficacy, and resilience to improve children's healthy behaviors and reduce the risk of developing obesity. Methods: This cluster randomized trial will involve 120 child day care centers and public nursery schools across Catalonia and Madrid, Spain, engaging 1,200 families with children aged 0 to 5 years. The study will evaluate children’s zBMI and health-related variables among children, parents/caregivers, and educators through both in-person and self-reported measures. The intervention will unfold in three phases: a 10-month cycle of family group and individual workshops, along with pedagogical and communication materials in the short term. Follow-up and ongoing support will continue up to age 12 in the mid- and long-term phases. Discussion: The study's strengths include a holistic, flexible approach, long-term follow-up, emphasis on educator training, and socioeconomic equity. Moreover, it will address challenges like self-selection bias and attrition. Overall, the PRESAFALIN study aims to provide valuable insights into how early interventions on parental psychosocial factors determine childhood obesity, guiding scalable public health strategies. Trial Registration: This study protocol is registered and approved in the ISRCTN registry (ISRCTN 15553317).