## 3 Results
### Methodological Quality and Risk of Bias Assessment  
The methodological quality and risk of bias assessment of the 12 included studies was conducted using both the PEDro scale and the Cochrane Collaboration's risk of bias tool to provide comprehensive evaluation of internal validity as suggested by recent methodological guidelines (Table 2, Figure 2). Both assessment frameworks revealed consistent patterns of methodological limitations across the evidence base. The PEDro scale evaluation showed generally satisfactory methodological quality, with five studies receiving good ratings (scores of 6-7/10) [41; 43; 45; 48; 50] and seven studies receiving fair ratings (scores of 4-5/10) [40; 42; 44; 46; 47; 49; 51]. The Cochrane assessment corroborated these findings, with adequate randomization procedures demonstrated in only one study (8%) [45], while eleven studies (92%) showed some concerns regarding randomization processes [40; 41; 42; 43; 44; 45; 47; 48; 49; 51].  
The most prominent methodological limitation identified by both assessment tools was the universal absence of participant and personnel blinding across all twelve studies [40; 41; 42; 43; 45; 46; 47; 48; 50], representing an inherent constraint of lifestyle interventions where blinding to nutritional education and physical activity programs is impossible. Assessor blinding presented more substantial concerns, being absent in nine studies (75%) [42; 43; 45; 46; 47; 48; 50; 51], while only three studies achieved some concerns regarding outcome assessor blinding [40; 41; 44]. Incomplete outcome data showed mixed results with five studies achieving adequate handling [41; 43; 45; 48; 50], two studies showing concerns [46; 47], and five studies presenting high risk [40; 42; 44; 49; 51]. These findings resulted in high overall risk of bias ratings for all included studies according to Cochrane criteria.  
\begin{table}
\begin{tabular}{l c c c c c c c c c c c} \hline Random allocation & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\ Concealed allocation & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 \\ Baseline comparability & 1 & 1 & 1 & 1 & 1 & 1 & 0 & 1 & 1 & 1 & 1 & 1 \\ Blinding of subjects & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ Blinding of therapists & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ Blinding of assessors & 1 & 1 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 \\ Adequate follow-up (\textgreater{}85\%) & 0 & 1 & 0 & 1 & 0 & 1 & 1 & 1 & 0 & 1 & 0 \\ Intention-to-treat analysis & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 0 & 1 & 0 & 1 & 0 \\ Between-group statistical & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\ comparisons & & & & & & & & & & & & \\ Point estimates and & & & & & & & & & & & & \\ measures of variability for & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\ at least one key outcome & & & & & & & & & & & & \\ \hline
**Score** & 5 & 7 & 4 & 6 & 5 & 7 & 4 & 5 & 6 & 4 & 6 & 4 \\
**Cut-off points** & Fair & Good & Fair & Good & Fair & Good & Fair & Good & Fair & Good & Fair \\ \hline \end{tabular}
\end{table}
Table 2: Methodological assessment of the included studies (PEDro scale).  
Despite these methodological limitations, the convergent findings from both assessment frameworks strengthen confidence in the evidence synthesis. The consistency of beneficial effects across multiple independent studies with similar risk profiles provides reasonable support for the robustness of conclusions. However, results should be interpreted with appropriate caution given the potential for performance and detection bias to influence reported outcomes, particularly recognizing that the inability to blind participants and personnel in lifestyle interventions may lead to overestimation of treatment effects. The dual assessment approach provides comprehensive evaluation of study quality while acknowledging the inherent methodological constraints of school-based intervention research.