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Table 3 Summary of findings from included studies

From: A systematic review and meta-analysis of school-based interventions with health education to reduce body mass index in adolescents aged 10 to 19 years

Author, Year, Country, Name of Cohort/ study, Citation Study design, Participant characteristicsa Key Intervention characteristics Main findings and results for BMI/BMI z-score outcomes b
Low Risk of Bias
 Robbins, 2020 [66], USA
 GOAL
Pre test–post-test quasi-experimental design
Mean age 11.6 (0.09)
Intervention: n = 38
Control: n = 43
A total of 81 parent-student dyads were recruited
• Primary outcomes: feasibility and acceptability (qualitative), MVPA, diet quality, psychosocial variables (motivation, self-efficacy, and perceived social support for PA and healthy eating
• Duration of intervention: 12 weeks
• Follow up post intervention
• Teacher training: not needed as delivered by instructors and managers with experience in nutrition programmes (for the after-school clubs)
• Parental involvement: parent- student dyad combined meetings
• Digital component: Facebook participation with weekly healthy eating and PA habit forming tasks for parents to help adolescents with MVPA and diet
• Behaviour change theory: Self-determination theory and information-motivation-behaviour skills (IMB) model
Proportion of overweight and obese:
Intervention group: Baseline and post intervention 55.9% (p = 1.00)
Control group
Baseline 40.5%
Follow up 50.0% (p = 0.13)
 Robbins 2020 [67], USA and Pfeiffer et al. (2019) [47], USA Girls on the Move Group RCT
Mean age 12.07 (girls)
Intervention: n = 593
Control: n = 601
(schools in low-income areas)
• Primary outcome: MVPA, BMI Z score, Percentage body fat and cardiorespiratory fitness
• Duration of intervention: 17 weeks
• Follow up: immediate post-intervention and 1–4 weeks after intervention was completed
• Delivered by trained nurse and community-based instructors
• Digital component: one interactive internet-based session providing motivational and feedback messages
• Parental involvement: None during intervention period
• Behaviour Change Theory: Health promotion model and Self-determination theory
No significant differences occurred for BMI z score post intervention (B = − 0.02, P = 0.232)
Intervention
Baseline 1.30 (0.74)
Post intervention 1.30 (0.74)
Control
Baseline 1.42 (0.73)
Follow up 1.44 (0.73)
Unadjusted effect Size Cohen d = − 0.03
(subset analysis based on attendance (days/ week) provided but did not show any effect on BMI outcomes.
1–4 week Follow up results:
Control (766): 12.05 years.
Intervention (753): 12.05 years.
No significant between-group differences in BMI-z existed at post intervention (B = − 0.02, .191, 95% confidence
interval [CI; − 0.05-0.01]).
 Wadolawska, 2019 [60], Poland Non-randomised study with control group
Mean age: 11.9 (11.9–12.0)
Intervention n = 319
Control n = 145
• Primary outcome: Physical activity, sedentary time, diet and body composition (z-Waist to height Ratio, Z BMI for age, Waist circumference)
• Duration of intervention: 3 weeks
• Follow up: 9 months after baseline
• Delivered by researchers
• Digital component: None
• Parental involvement: None
• Behaviour change theory: Integrated theory
Change in z-BMI-for-age SDs (Follow up ̶ baseline):
Int: − 0.01 (− 0.07 to 0.04)
Con: 0.03 (− 0.01 to 0.07)
Difference: − 0.04
 Bogart, 2016d [48] USA RCT
Mean age: 12.2 (0.68)
Intervention: n = 829
Control: n = 539
• Primary outcome: BMI percentile
• Duration of intervention: 5 weeks
• Follow up after intervention: 2 years
• Teacher training: Delivered by peer leaders and teachers (training given to peer leaders).
• Parental involvement: Homework activities with parents
• Behaviour change theory: Social cognitive theory and community based participatory research
BMI percentile (intervention versus control): adjusted difference = − 0.98 (SE 1.01), p = 0.33
Subset analysis (students obese at baseline)
BMI percentile adjusted b = −2.33 (SE 0.83; P = 0.005) compared with control students.
 Lubans, 2016 [42] and Smith 2014 [68], Australia
 ATLAS
Cluster RCT
Mean age: 12.7 (0.5)
Intervention: n = 121
Control: n = 143
• Primary outcome: BMI, waist circumference
• Duration of intervention: 8 months
• Follow up: immediately after intervention and 18 months from baseline
• Teacher training: two 6-h workshops
• Digital component: smartphone app and website.
• Parental involvement: Parent newsletters.
• Behaviour change theory: self-determination theory and social cognitive theory
BMI z-score (adjusted mean difference) at 18 months from baseline:
0.04 (95%CI: − 0.07 to 0.14)
 Melnyk, 2015 [53], USAc
 COPE
Cluster RCT
Mean age: 14.74 (0.73)
Intervention: n = 358
Control: n = 421
• Primary outcome: BMI and depressive symptoms
• Intervention duration: 15 weeks
• Follow up after intervention: 12 months
• Teacher training: full day training workshop
• Digital component: None reported
• Parental involvement: Newsletter provided and students were expected to discuss with parents
• Behaviour change theory: cognitive theory
BMI at 12 months adjusted mean
COPE teens (24.94, SE 0.12)
Control group (25.48, SE 0.11)
p-value for difference = 0.001
 Viggiano, 2015 [45], Italyc
 Kaledo
RCT
Mean age 13.0 (12.9–13.0)
Intervention: n = 1663
Control: n = 1447
• Primary outcomes: dietary behaviours and BMI z-scores
• Duration of intervention: 20 weeks
• Follow up: 6 and 18 months post baseline
• Teacher training: teachers trained in playing the game
• Digital component: None reported
• Parental involvement: None reported
• Behaviour change theory: Not specified
BMI z-scores
At 6 month follow-up:
Middle schools:
Intervention: 0.49 (95%CI: 0.45 to 0.53)
Control: 0.58 (95%CI: 0.54 to 0.62)
p-value for difference = 0.007
High schools:
Intervention: 0.35 (95%CI: 0.29 to 0.40)
Control: 0.57 (95%CI: 0.51 to 0.63)
p-value for difference < 0.001
At 18 month FU:
Middle schools:
Intervention: 0.40 (95%CI: 0.28 to 0.52)
Control: 0.57 (95%CI: 0.44 to 0.71)
p-value for difference = 0.057
High schools:
Intervention: 0.13 (95%CI: − 0.09 to 0.34)
Control: 0.61 (95%CI 0.31 to 0.90)
p-value for difference = 0.015
 Dewar, 2013 [36], Australia
 Neat Girls
RCT
Mean age 13.2 (0.5)
Intervention n = 178, Control n = 179
Girls only
• Primary outcomes: BMI
• Duration of intervention: one year
• Follow up at 12 months and 24 months (12 months post intervention)
• Teacher training: 1-day training workshop.
• Digital component: SMS
• Parental involvement: Parent newsletters
• Behaviour change theory: Social cognitive theory
Adjusted BMI z-score change at 12 month post intervention:
− 0.12 (95%CI: − 0.27, 0.04)
 Ezendam, 2012 [50], Netherlands
 FATaintPHAT
RCT
Mean age (control group): 12.7 (0.7
Control: 340
Intervention: 395
• Primary outcomes: Waist circumference, BMI and fitness
• Duration of intervention: 10 weeks
• Follow up at 4 months and 2 years
• Teacher training: manual provided
• Digital component: primarily an internet-based intervention
• Parental involvement: None reported
• Behaviour change theory: Theory of Planned Behaviour
Not reported for 4-month follow-up.
BMI change at 2 years between group difference: − 0.14 (95%CI: − 0.17 to 0.45)
 Robbins, 2012 [44], USA
 Pilot study Girls on the Move
Quasi-experimental study
Mean age: 11.4 years
Intervention: n = 37
Control: n = 32
• Primary outcomes: BMI, physical activity, and cardiovascular fitness
• Duration of intervention: 6 months
• Follow up after intervention: immediately post intervention
• Teacher training: Motivational Interviewing training for the school nurse
• Digital component: None reported
• Parental involvement: None reported
• Behaviour change theory: health promotion model
BMI z-score change:
Intervention: 0.06 (0.18)
Control: 0.12 (0.18)
Adjusted difference: − 0.04 (p = 0.24)
 Prins, 2012 [57], Netherlands RCT
Mean age: 12.7 (0.5)
Intervention: 281
Control: 254
• Primary outcomes: Compliance with MVPA guideline and minutes spent in MVPA
• Duration of the intervention: Not reported
• Follow up at one and six months post intervention
• Teacher training: Manual provided
• Digital component: Computer tailored PA promotion
• Parental involvement: None reported
• Behaviour change theory: Socio-ecological model
Unstandardized regression coefficient (95% CI) for prevalence of overweight and obesity at 6 month follow-up: 0.16 (95%CI: − 1.01 to 1.13).
 The HEALTHY study group, 2010 [52], USAc RCT
Mean age 11.3 (0.6)
Intervention: 4603
Control: 2296
• Primary outcomes: Risk of diabetes (BMI, waist circumference, fasting glucose and insulin levels), combined prevalence of OWO
• Duration of intervention: 3 years
• Follow up at 3 years from baseline
• Teacher training: 4 h training with companion manual
• Digital component: None
• Parental involvement: newsletters matching theme of semester
• Behaviour change theory: Social cognitive theory
Change in BMI z-score:
Intervention: − 0.05
Control group: − 0.01
 Peralta, 2009 [56], Australia
 FILA study (Fitness Improvement Lifestyle Awareness)
RCT
Mean age 12.5 (0.4)
Intervention: n = 16
Control: n = 17
Boys only
• Primary outcome: BMI
• Follow up after intervention: 6 months
• Teacher training: None (delivered by researcher)
• Digital component: None reported
• Parental involvement: Newsletters
• Behaviour change theory: social cognitive theory
Adjusted BMI difference between intervention and control:
− 0.2 (95%CI: − 0.78 to 0.39), p = 0.5
 Singh, 2007 [59], The Netherlands
 DOiT (Dutch Obesity Intervention in Teenagers)
RCT
Mean age (control) 12.8 (0.51)
Total n = 978
• Primary outcomes: BMI, measures of body fatness and aerobic fitness
• Duration of intervention: 8 months
• Follow up immediately after intervention
• Teacher training: Teachers received a manual to support them in delivering the intervention
• Digital component: Individual advice provided by CD rom
• Parental involvement: None reported
• Behaviour change theory: Not specified
BMI (difference between intervention and control in change between groups):
Girls: − 0.05 (95%CI: − 0.18 to 0.08)
Boys: − 0.02 (95%CI: − 0.11 to 0.16)
Medium Risk of Bias
 Ermetici, 2016 [37], Italyc
 EAT Study
Non-randomised quasi-experimental study
Mean age 12.5 (0.4)
Intervention: n = 262
Control: n = 225
• Primary outcome: BMI Z-score
• Intervention duration: 2 school years
• Follow up after intervention: Immediate post intervention
• Teacher training: Text book to aid lessons
• Digital component: Automated text messages
• Parental involvement: Text messages
• Behaviour change theory: not specified
After 2 years, BMI z-score (adjusted difference):
- 0.18 (95%CI: − 0.27 to − 0.09), p = 0.003
 Wilksh, 2015, Australia [62] Four arm RCT with multiple educational modules
Mean age: 13.21 (0.68)
Media Smart (MS): N = 269
Life Smart (LS): N = 347
HELPP (HP): N = 225
Control (C): N = 473
• Primary outcome: risk of eating disorders
• Duration of intervention (LifeSmart): 5 weeks
• Follow up after intervention: post program, 6 month and 12 months
• Teacher training: None reported
• Digital component: None reported
• Parental involvement: None reported
• Behaviour change theory: not specified
Group by time effect showed no significant effects on BMI for boys or girls at 12 month follow up.
 Lazorick, 2015 [41], USc
 The MATCH Intervention
Two armed quasi-experimental study
Mean age: 13.3 (0.79)
Intervention: n = 189
Control: n = 173
• Primary outcome: BMI and BMI Z-score
• Intervention duration: 14 weeks
• Follow up after intervention: post intervention and one year
• Teacher training: One day of teacher training provided and a two-day orientation
• Digital component: None reported
• Parental involvement: None reported
• Behaviour change theory: Social cognitive and self-determination theory
Mean change BMI z-score immediately post intervention
Intervention: − 0.06 (95%CI: − 0.08 to − 0.03)
Control: 0.02 (95%CI: − 0.004 to 0.05)
p-value for difference < 0.001
 Grydeland, 2014 [40], Norwayd
 HEIA Intervention Study
Two armed RCT.
Mean age = 11.2 (0.3)
Intervention: n = 465
Control: n = 859
• Primary outcome: BMI and BMI Z-score
• Intervention duration: 20 months
• Follow up after intervention: immediate post intervention
• Teacher training: PE teachers were enrolled in a course
• Digital component: Computer tailored individual advice
• Parental involvement: Parent-based fact sheets
• Behaviour change theory: socio-ecological framework
Post intervention BMI z-score (adjusted for baseline values)
Girls
Intervention: − 0.8 (95%CI: − 0.14, − 0.02)
Control: 0.03 (95%CI: − 0.01, 0.08)
p-value for difference = 0.003
Boys
Intervention: − 0.01 (− 0.07, 0.05)
Control: − 0.05 (95%CI: − 0.09, − 0.00)
p-value for difference = 0.32
Total
Intervention: − 0.04 (95%CI: − 0.09, 0.00)
Control: − 0.01 (95%CI: − 0.04, 0.02)
p-value for difference = 0.227
 Bonsergent, 2013 [35], France
 PRALIMAP
RCT
Mean age 15.6 (0.7)
Intervention: 3424
Control: 2947
• Primary outcomes: BMI and BMI Z-score
• Duration of intervention: 24 months
• Follow up: at 12 months and immediately post intervention
• Teacher training: None reported
• Digital component: None reported
• Parental involvement: None reported
• Behaviour change theory: None reported
BMI z-score change at 12 months post intervention:
β = 0.004 (95%CI: − 0.026, 0.034)
 Fairclough, 2013 [38], UKc
 The CHANGE! Intervention
RCT
Mean age (control group): 10.7 (0.3)
Control: 117
Intervention: 89
• Primary outcomes: Waist circumference, BMI and BMI z-score
• Duration of intervention: 20 weeks
• Follow up at immediately post intervention (20 weeks) and 30 weeks
• Teacher training: 4 h in how to deliver the curriculum
• Digital component: CD ROM
• Parental involvement: None reported
• Behaviour change theory: Social cognitive theory
BMI z-score adjusted change at 20 weeks:
β = − 0.04 (95% CI: − 0.22, 0.15), p = 0.68
BMI z-score adjusted change at 30 weeks:
β = − 0.24 (95% CI: − 0.48, − 0.003), p = 0.04
 Williamson, 2012 [46], USA RCT
Mean age: 12.9 (1.2)
Intervention: PP = 511; PP+ SP = 516
Control: 307
• Primary outcomes: Percentage body fat and BMI z-score
• Duration of intervention: 28 months.
• Follow up at 18 months and 28 months (immediately post intervention).
• Teacher training: None reported
• Digital component: Online platform
• Parental involvement: Emails to parents.
• Behaviour change theory: Not reported.
Adjusted difference between control and intervention BMI z-scores at 28 months:
Boys: β = − 0.034
Girls: β = − 0.035
 Neumark-Sztainer, 2010 [55], US
 New Moves
RCT
Mean age: 15.8 (1.2)
Intervention: 182
Control: 174
Girls only
• Primary outcomes: Physical activity levels
• Duration of intervention: one school year.
• Follow-up at immediately post intervention and 9 months post intervention.
• Teacher training: None reported.
• Digital component: None reported.
• Parental involvement: Parent outreach and parent-daughter retreat days.
• Behaviour change theory: Social cognitive theory.
Adjusted BMI difference between groups at 9 month post intervention follow-up:
− 0.10, p = 0.446
 Mihas, 2009 [54], Greecec
VYRONAS study
RCT
Mean age (control) 13.3 (0.9)
Intervention: n = 98
Control: n = 93
• Primary outcomes: dietary habits and BMI
• Duration of intervention: 12 weeks
• Follow ups after intervention: 15 days and 12 months
• Teacher training: materials and two 3-h seminars
• Digital component: none reported
• Parental involvement: nutrition education and behaviour change
• Behaviour change theory: social learning theory
No change in BMI at 15 days
Mean BMI (adjusted) at 12 months vs baseline:
Int: 23.3 (SD 2.8) vs 24.0 (SD 3.1) p < 0.001
Con: 24.8 (SD 3.8) vs 24.3 (SD 3.3) p = 0.36
 Young, 2006 [63], USA RCT
Mean age 13.8 (0.5)
Intervention: n = 111
Control: n = 99
Girls only
• Primary outcomes: physical activity and markers of cardiovascular disease risk factors
• Duration of intervention: 8 months
• Follow up immediately after intervention
• Teacher training: not needed as intervention delivered by research staff
• Digital component: none reported
• Parental involvement: family workshops, monthly newsletters and parent/child homework
• Behaviour change theory: social action theory
Adjusted mean BMI change:
Intervention: 0.3 (SE 0.2) p = 0.2
Control: 0.2 (SE 0.2) p = 0.34
Between group p = 0.81
High risk of Bias
 Benitez-Andrades (2020),d [65] Spain Non-randomised pre-post quasi experimental study design with control group
Mean age: 12.8 for C and 12.6 for I
Intervention: n = 139
Control: n = 91
• Primary outcome: BMI age-adjusted percentile, physical activity, eating habits
• Duration of intervention: 14 weeks
• Follow up: immediately after intervention only
• Delivered by researchers
• Digital component: Facebook-based intervention
• Parental involvement: None
• Behaviour Change Theory: Not specified
Intervention group:
BMI age-adjusted percentile
(≥50 initial i.e. overweight)
Mean Pre: 77.59
Mean post: 72.85
Z: − 5.394
p = 0.000
Control group:
BMI age-adjusted percentile
(≥50 initial)
Mean pre: 78.09
Mean post: 77.49
Z = 0.241
p = 0.809
 Froberg, 2018 [64], Sweden Non-randomised study with control group
Mean age: 12.8 (0.5)
Intervention: 51
Control: 47
• Primary outcome: physical activity, food habits, and behaviour change
• Duration of intervention: 2 years
• Follow up: 2 years and 4 months from after baseline
• Delivered by researchers
• Digital component: Facebook group for communication between researchers and students, however main intervention was delivered in class.
• Parental involvement: None
• Behaviour change theory: empowerment-based health promotion, shared decision making
Non-adjusted mean difference in BMI between intervention and control: 1.9 (95% CI: 0.035, 3.76).
Change in prevalence for overweight: − 0.8%
Change in prevalence for obesity: 1.3%
 Busch, 2015 [49], The Netherlandsd
 Utrecht Healthy School (UHS)
Non-randomised controlled trial
Age group: high school students
1 year (N = 969)
2 years (N = 605).a
• Primary outcome: BMI, health behaviour and psychosocial health
• Intervention duration: The UHS was integrated into the school curriculum for 2 years
• Follow up after intervention: 1 and 2 years from baseline
• Teacher training: For teachers and head teachers
• Digital component: None reported
• Parental involvement: participation in school projects
• Behaviour change theory: not specified
Adjusted BMI change from baseline for interventions schools compared with control schools
School A
Year 1: β = − 0.48 (p < 0.05)
Year 2: β = − 0.58 (p < 0.05)
School B
Year 1: β = − 0.05 (p > 0.05)
Year 2: β = − 0.43 (p > 0.05)
 Millar, 2011 [43], USA c Quasi-experimental study
Mean age: 14.6 (1.42)
Intervention: n = 1276
Control: 778
• Primary outcomes: BMI, BMI z-score and body composition
• Duration of intervention: Not reported
• Follow up at (m; SD) 2.3 (0.68) years from baseline.
• Teacher training: CPD for PE teachers.
• Digital component: None reported.
• Parental involvement: parent information, family and home environment
• Behaviour change theory: Not reported.
Adjusted difference between intervention and control BMI z-scores at follow-up:
− 0.07 (SE 0.03), p = 0.03
 Graham, 2008 [51]
 Schneider, 2007 [69]
 USA
Non-randomised controlled trial
Mean age 15.04 (0.79)
Intervention: n = 63
Control: n = 59
Girls only
• Primary outcomes: Cardiovascular fitness and physical activity levels
• Duration of intervention: 9 months
• Follow up after immediately after intervention
• Teacher training: No teacher training described, unclear who delivered the intervention
• Digital component: None reported
• Parental involvement: None reported
• Behaviour change theory: not specified
No significant difference (p = 0.1) between groups in change in BMI percentile
 Webber, 2008 [61], US
 Trial of Activity for Adolescent Girls
 (TAAG)
Cluster RCT
Mean ages:
6th graders 12.0
8th graders 14.0
n = 1721 (6th grade 2003)
n = 3504 (8th grade 2005)
n = 3502 (8th grade 2006)
Girls only
• Primary outcomes: physical activity levels and body composition measurements
• Duration of intervention: 2–3 years
• Follow-ups: 2 and 3 years post baseline
• Teacher training: PE teachers and Program Champions were trained by TAAG investigators
• Digital component: None reported
• Parental involvement: None reported
• Behaviour change theories: operant learning theory, social cognitive theory, organizational change theory, and diffusion of innovation model
BMI mean difference:
6th grade (2003): − 0.2
(95%CI: − 1.0 to 0.6)
8th grade (2005): − 0.2
(95%CI: − 0.6 to 0.2)
8th grade (2006): 0.1
(95%CI: − 0.4 to 0.7)
 Foster, 2008 [39], USc(SNIP study (School Nutrition Policy Initiative) RCT
Mean age (control) 11.2 (1.0)
Intervention: n = 749
Control: n = 600
• Primary outcomes: incidence of overweight and obesity
• Duration of intervention: 2 years
• Follow-up immediately after intervention
• Teacher training: Teachers were offered up to 10 h of training per year
• Digital component: None reported
• Parental involvement: Parent outreach
• Behaviour change theory: Not specified
BMI (adjusted difference):
− 0.04 (95%CI: − 0.27 to 0.19), p = 0.71
BMI z-score (adjusted difference):
− 0.01 (95%CI: − 0.08 to 0.06), p = 0.80
Predicted odds ratio for incidence of overweight (adjusted): 0.67 (95%CI: 0.47 to 0.96) p < 0.05
 Rosenbaum, 2007 [58], USA c RCT
Mean age (control) 13.6 (0.2)
Intervention: n = 49
Control: n = 24
• Primary outcomes: Markers of insulin sensitivity and inflammation
• Duration of intervention: 3–4 months
• Follow up immediately after intervention
• Teacher training: None (delivered by researchers)
• Digital component: None reported
• Parental involvement: None reported
Behaviour change theory: Not specified
BMI at baseline and follow-up:
Control: 24.3 (SD: 1.8) to 24.8 (SD: 1.9)
p ≥ 0.05
Intervention: 24.7 (SD: 1.4) to 24.0 (SD:1.5) p < 0.05
 Amaro, 2006 [34], Italy,
 Kaledo pilot (See Viggiano, 2015 [45])
RCT
Mean age (control) 12.5 (0.7)
Intervention: n = 153
Control: n = 88
• Primary outcomes: dietary behaviours and BMI Z-score
• Duration of intervention: 24 weeks
• Follow up: immediately after intervention
• Teacher training: teachers trained in playing the game.
• Digital component: None reported
• Parental involvement: None reported
• Behaviour change theory: Not specified
BMI z-score (adjusted mean controlling for baseline values):
Intervention: 0.35 (95CI%: 0.30 to 0.39)
Control: 0.41 (95%CI: 0.35 to 0.47)
  1. aSome studies only reported age by group or group and sex, but were similar in both groups; Where sample size for intervention and control groups are not reported, total size is presented
  2. bMD (95%CI), p-value reported when available
  3. cStudies with significant effects on BMI outcomes
  4. dSignificant effect in a subset analysis