## 1 Introduction  
Child and adolescent overweight and obesity constitute a rapidly escalating global public-health concern [1, 2, 3, 4]. The World Health Organization estimates that, over the past three decades, the number of young people with excess body weight has more than doubled, and projections point to a continued rise [5]. Particularly alarming is the robust association between an elevated body-mass index (BMI) in childhood and the early onset of chronic diseases, type 2 diabetes, hypertension, dyslipidemia and cardiovascular disease, the effects of which persist into adulthood [6]. In addition, these consequences could be aggravated considering that up to 81% of children are inactive globally [7]. Accumulating evidence indicates that childhood adiposity predicts arterial stiffness, cardiac remodeling and subclinical atherosclerosis in later life, irrespective of subsequent changes in body weight [8, 9]. Moreover, overweight sustained across the life course exerts a cumulative impact on adipokine secretion, inflammatory pathways and, potentially, endothelial function [10]. These findings highlight the urgent need for early preventive and therapeutic strategies that address not only body weight but also key cardiometabolic biomarkers, with the aim of altering the trajectory towards chronic disease before it becomes firmly established. Adopting a physically active lifestyle in the early years is associated with a markedly higher likelihood of maintaining healthy behaviors in adulthood [11]. In this regard, the school environment represents an ideal setting for promoting healthy habits and preventing obesity, given the substantial amount of time children spend there during a particularly sensitive developmental stage [12, 13]. School-based interventions commonly incorporate nutritional education and structured physical-activity programs [14, 15, 16]. With respect to nutrition, the extant literature supports the notion that a healthy dietary pattern exerts direct beneficial effects on various biomarkers in childhood [17, 18]. Controlled trials have demonstrated significant reductions in total cholesterol, triglycerides and LDL concentrations [19, 20]. Low-glycemic-load diets and appropriately balanced macronutrient distributions have also been linked to improved insulin sensitivity, especially in school-age children with elevated baseline insulin levels [21]. These effects are even more consistent when dietary counselling is initiated in early childhood and maintained throughout the primary-school years [22]. Regular physical exercise is regarded as one of the most effective adjuvant therapies for enhancing metabolic health in children with overweight or obesity [23, 24, 25, 26]. A systematic review of 29 trials (n = 2195) showed that programs combining moderate-to-vigorous aerobic activity with resistance training significantly reduce body fat, increase VO2 max and foster a more favorable lipid profile in this population [27]. Such interventions also lower fasting insulin and the HOMA-IR index, indicating enhanced insulin sensitivity [28]. The extensive evidence supporting the benefits of physical-activity and nutritional interventions has spurred the development of multicomponent programs that integrate both elements. These interventions have yielded synergistic effects that surpass those achieved by single-component approaches in adolescents [29], adults [30] and older adults [31]. School initiatives that combine exercise and nutrition, involve parents and staff, and are grounded in theoretical frameworks have been shown to produce greater improvements in child health outcomes, including weight status [4]. Accordingly, school-based strategies that integrate daily movement and balanced nutrition emerge as essential tools for the early prevention of metabolic syndrome and other chronic conditions.