Problematic Smartphone Use, Physical Activity, and Obesity Risk in Children and Adolescents: A Narrative Review

Background Problematic smartphone use (PSU) has been associated with physical inactivity, mental health symptoms, and excess body weight in young people. However, its specific contribution beyond overall screen time and the mechanisms underlying these associations remain unclear. Aim To examine associations between PSU, physical activity, and obesity risk in children and adolescents, including potential psychological and behavioral pathways and relevant interventions. Materials and Methods A narrative review was conducted using PubMed and Google Scholar in September 2026. Forty-five sources published between 2010 and 2026 were included, comprising observational and intervention studies, systematic reviews, other literature reviews, and meta-analyses. The review focused on children and adolescents, with selected studies of young adults included as supplementary evidence. Results Studies reported associations between PSU, lower physical activity, and overweight or obesity, although findings varied. Reduced smartphone use was associated with increased physical activity in some studies, while exercise interventions reduced PSU scores. A cross-sectional mediation analysis identified indirect statistical associations with BMI z-scores through depressive symptoms and eating behaviour scores, without establishing causality. Sleep disturbances were also associated with PSU. Activity trackers increased daily step counts in a meta-analysis but did not significantly improve moderate-to-vigorous physical activity. Conclusions PSU is associated with physical activity and weight-related outcomes, but heterogeneous and predominantly observational evidence limits causal interpretation. Reducing smartphone use and promoting exercise may improve selected behavioural outcomes; their effectiveness in preventing obesity remains unestablished. Long-term prospective and intervention studies are needed to clarify these relationships and evaluate preventive strategies.