Comparison 8. BMI z‐score.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
8.1 BMI z‐score	17	4766	Mean Difference (IV, Random, 95% CI)	‐0.03 [‐0.09, 0.03]
8.2 BMI z‐score (sensitivity: studies at low overall risk of bias)	14	3645	Mean Difference (IV, Random, 95% CI)	‐0.01 [‐0.08, 0.06]
8.3 BMI z‐score (Health Promoting Schools: curriculum versus no curriculum)	17	4766	Mean Difference (IV, Random, 95% CI)	‐0.03 [‐0.09, 0.03]
8.3.1 Curriculum	12	3867	Mean Difference (IV, Random, 95% CI)	‐0.03 [‐0.09, 0.04]
8.3.2 No curriculum	5	899	Mean Difference (IV, Random, 95% CI)	0.00 [‐0.17, 0.18]
8.4 BMI z‐score (SES: low versus high/unclear)	17	4766	Mean Difference (IV, Random, 95% CI)	‐0.03 [‐0.09, 0.03]
8.4.1 Low	10	2193	Mean Difference (IV, Random, 95% CI)	‐0.01 [‐0.11, 0.08]
8.4.2 High/unclear	7	2573	Mean Difference (IV, Random, 95% CI)	‐0.04 [‐0.13, 0.06]
8.5 BMI z‐score (study size: small (< 400 participants) versus large (≥ 400 participants))	17	4766	Mean Difference (IV, Random, 95% CI)	‐0.03 [‐0.09, 0.03]
8.5.1 Small (< 400 participants)	14	2935	Mean Difference (IV, Random, 95% CI)	‐0.04 [‐0.12, 0.04]
8.5.2 Large (≥ 400 participants)	3	1831	Mean Difference (IV, Random, 95% CI)	‐0.01 [‐0.10, 0.09]