Family matters? A Systematic review of interventions addressing family-level mechanisms in the treatment of childhood and adolescent obesity.

Family systems are a key influencing factor in the development and maintenance of overweight and obesity in childhood and adolescence with family-based interventions being considered the gold standard in paediatric weight management. So-called second-order level mechanisms, underlying family processes such as communication, parenting skills, and organisational abilities are of particular importance for sustaining family-level behavioural changes and improved health outcomes. This systematic review synthesises interventions that integrate such mechanisms and their impact on health- and weight related outcomes. A systematic literature search was conducted in PubMed, PsycInfo, Web of Science, and the Cochrane Library following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The initial search yielded 16,129 records, after a multistep process including two independent reviewers, n = 22 studies met the final inclusion criteria. Second-order level mechanisms addressed included parenting skills and practices (n = 11), parent-child relationships and communication (n = 6), family functioning and dynamics (n = 4), home and family environment (n = 3), and cultural and family values (n = 3), with several interventions addressing multiple mechanism clusters. n = 9 studies reported significant weight-related changes. Psychosocial and behavioral outcomes, when reported, showed improvements in health-related quality of life, family health routines, nutrition knowledge, and self-efficacy. This systematic review provides an integrative overview of family-based interventions utilising second-order level family mechanisms as structural and relational processes that may support the sustainability of change. The results offer a valuable framework for understanding how families regulate and maintain health behaviours beyond isolated behavioural components.