Evaluated School-Based Exercise Interventions with Nutritional Supplementation in Obese Children and Adolescents: A Systematic Review of Randomized Controlled Trials for Highlighting a Research Gap

Background/Objectives: The systematic review aims to highlight the effects of school-based physical activity and nutritional supplementation programs in obese children from preschool to high school, based on randomized controlled trials. Methods: The search strategy was designed based on the PICOS framework. Then, a systematic review of relevant articles was conducted across six databases (Cochrane Library, PubMed, ProQuest, SCOPUS, Web of Sciences and SPORTDiscus) to identify articles that included children from preschool to high school who engaged in physical activity at school and received nutritional supplementation. All the included studies were assessed using the RoB-2 checklist. Results: Of the 234 studies reviewed, six met the inclusion criteria for this systematic review (publication years: 2023–2025). The results revealed highly heterogeneous interventions and mixed outcomes, often influenced by factors such as supplement type, dosage and participant gender. This limited and inconsistent body of evidence underscores a significant gap in the literature concerning the combined effects of school-based exercise and nutritional supplementation in obese youth. Conclusions: Limited evidence suggests mixed results with multi-micronutrient supplementation showing some benefits in boys from resource-limited settings, while several interventions demonstrated no effects. Energy-dense supplementation proved counterproductive. Gender-stratified approaches are recommended, but cautious implementation is warranted given methodological limitations and inconsistent findings.