ABSTRACT

OBJECTIVE

To evaluate the implementation and effectiveness of school-based interventions to prevent obesity conducted in Latin America and provide suggestions for future prevention efforts in countries of the region.

METHODS

Articles published in English, Spanish, and Portuguese between 2000 and 2017 were searched in four online databases (Google Scholar, PubMed, LILACS, and REDALYC). Inclusion criteria were: studies targeting school-aged children and adolescents (6–18 years old), focusing on preventing obesity in a Latin American country using at least one school-based component, reporting at least one obesity-related outcome, comprising controlled or before-and-after design, and including information on intervention components and/or process.

RESULTS

Sixteen studies met the inclusion criteria. Most effective interventions (n = 3) had moderate quality and included multi-component school-based programs to promote health education and parental involvement focused on healthy eating and physical activity behaviors. These studies also presented a better study designs, few limitations for execution, and a minimum duration of six months.

CONCLUSIONS

Evidence-based prevention experiences are important guides for future strategies implemented in the region. Alongside gender differences, an adequate duration, and the combined use of quantitative and qualitative evaluation methods, evidence-based prevention should be considered to provide a clearer and deeper understanding of the true effects of school-based interventions.

Child; Adolescent; Obesity, prevention & control; Evaluation of the Efficacy-Effectiveness of Interventions; School Health Services; Review

INTRODUCTION

Childhood obesity is a global public health problem. The worldwide trend showed that, in 2013, 22.6% of girls and 23.8% of boys in developed countries were overweight or obese, whereas in developing countries it was 13% for both girls and boys ¹1. Ng M, Fleming T, Robinson M, Thomson B, Graetz N, Margono C, et al. Global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet. 2014;384(9945):766-81. https://doi.org/10.1016/S0140-6736 (14)60460-8
https://doi.org/10.1016/S0140-6736 (14)6... . Recently, a study on the trends from 1975 to 2016 estimated the global-age standardized prevalence of obesity in children and adolescents to be 5.6% among girls and 7.8% among boys, highlighting the sustained growth in developing countries ²2. Abarca-Gomez L, Abdeen ZA, Hamid ZA, Abu-Rmeileh NM, Acosta-Cazares B, Acuin C, et al. Worldwide trends in body-mass index, underweight, overweight, and obesity from 1975 to 2016: a pooled analysis of 2416 population-based measurement studies in 128.9 million children, adolescents, and adults. Lancet. 2017;390(10113):2627-42. https://doi.org/10.1016/S0140-6736 (17)32129-3
https://doi.org/10.1016/S0140-6736 (17)3... .

Latin America follows this trend: in 2016, the prevalence of overweight and obesity among 5 to 19 year-old Mexican children and adolescents ranged between 33% (both genders, aged 5–11 years) and 39.2% (girls aged 12–19 years; boys: 33.5%) ³3. Shama-Levy T, Cuevas-Nasu L, Gaona-Pineda EB, Gomez-Acosta LM, Morales-Ruan MDC, Hernandez-Avila M, et al. Sobrepeso y obesidad en niños y adolescentes en México, actualización de la Encuesta Nacional de Salud y Nutrición de Medio Camino 2016. Salud Publica Mex. 2018;60(3):244-53. https://doi.org/10.21149/8815
https://doi.org/10.21149/8815... . Country-specific data from the Global Burden of Disease (GBD) 2015 Obesity Collaborators shows that in Chile the prevalence was 25.5% among girls and 36.4% among boys, and in Brazil 23.8% among girls and 27.3% boys (< 20 years old) ⁴4. The GBD 2015 Obesity Collaborators. Health effects of overweight and obesity in 195 countries over 25 years. New Engl J Med. 2017;377(1):13-27. https://doi.org/10.1056/NEJMoa1614362
https://doi.org/10.1056/NEJMoa1614362... . As for Peru, GBD found 22.4% of girls and 19.2% of boys to be overweight or obese.

Environmental factors, lifestyle preferences, and cultural environments play key roles in the worldwide rising prevalence of obesity ⁵5. Dehghan M, Akhtar-Danesh N, Merchant AT. Childhood obesity, prevalence and prevention. Nutr J. 2005;4:24. https://doi.org/10.1186/1475-2891-4-24
https://doi.org/10.1186/1475-2891-4-24... . Numerous studies showed that sugary beverages and high-fat foods consumption added to low fruit and vegetable intake, decreased physical activity (PA), and increased sedentary behavior is positively associated with obesity ⁶6. Mitchell JA, Mattocks C, Ness AR, Leary SD, Pate RR, Dowda M, et al. Sedentary behavior and obesity in a large cohort of children. Obesity (Silver Spring). 2009;17(8):1596-602. https://doi.org/10.1038/oby.2009.42
https://doi.org/10.1038/oby.2009.42... .

This evinces the importance in promoting healthier food choices and a more active lifestyle along with environment-related changes to improve healthy behavior in school-aged children and adolescents ⁹9. De Bourdeaudhuij I, Van Cauwenberghe E, Spittaels H, Oppert JM, Rostami C, Brug J, et al. School-based interventions promoting both physical activity and healthy eating in Europe: a systematic review within the HOPE project. Obes Rev. 2011;12(3):205-16. https://doi.org/10.1111/j.1467-789X.2009.00711.x
https://doi.org/10.1111/j.1467-789X.2009... . Schools play a pivotal role in promoting a healthy lifestyle among students. Reviews on school-based prevention programs for obesity, mostly in the United States and Europe, reported improvement in health-related behaviors and/or knowledge, as well as some positive impacts on body mass index (BMI) ⁹9. De Bourdeaudhuij I, Van Cauwenberghe E, Spittaels H, Oppert JM, Rostami C, Brug J, et al. School-based interventions promoting both physical activity and healthy eating in Europe: a systematic review within the HOPE project. Obes Rev. 2011;12(3):205-16. https://doi.org/10.1111/j.1467-789X.2009.00711.x
https://doi.org/10.1111/j.1467-789X.2009... .

Reviews on the extent and impact of interventions conducted in Latin America targeting obesity among school-aged children and adolescents are scarce. Most reviews are based on international efforts and include few studies conducted in Latin America, or approach PA interventions and report only PA-related outcomes ¹⁰10. Sharma M. International school-based interventions for preventing obesity in children. Obes Rev. 2007;8(2):155-67. https://doi.org/10.1111/j.1467-789X.2006.00268.x
https://doi.org/10.1111/j.1467-789X.2006... , ¹²12. Verstraeten R, Roberfroid D, Lachat C, Leroy JL, Holdsworth M, Maes L, et al. Effectiveness of preventive school-based obesity interventions in low-and middle-income countries: a systematic review. Am J Clin Nutr. 2012;96(2):415-38. https://doi.org/10.3945/ajcn.112.035378
https://doi.org/10.3945/ajcn.112.035378... . A review performed in 2013 reported significant outcomes in seven of the ten included studies, among which at least three presented an appropriate design and execution conducive to statistically significant changes in obesity-related outcomes ¹⁶16. Lobelo F, Garcia de Quevedo I, Holub CK, Nagle BJ, Arredondo EM, Barquera S, et al. School-based programs aimed at the prevention and treatment of obesity: evidence-based interventions for youth in Latin America. J Sch Health. 2013;83(9):668-77. https://doi.org/10.1111/josh.12080
https://doi.org/10.1111/josh.12080... .

Considering that our systematic review seeks to assess how obesity prevention interventions targeting school-aged children and adolescents were implemented in different Latin American countries (i.e. implementation) and whether they were effective on obesity-related outcomes (i.e., effectiveness). Based on these findings, we provide suggestions for future prevention efforts implemented in Latin American countries.

METHODS

Literature Search

Studies published from 2000 to 2017 were collected by searching four online databases: Google Scholar, PubMed, Literature in the Health Sciences in Latin America and the Caribbean (LILACS), and the Network of Scientific Journals of Latin America and the Caribbean, Spain, and Portugal (REDALYC). An update search was conducted in March 2019. Potentially eligible articles were also located by hand, by screening studies and articles reference list, across the 20 Latin American countries. Search strategy included Medical Subject Headings (MeSH) terms combined with text words based on the categories: population, intervention, outcomes, and type of studies addressed by the review. Search strategy is available at https://osf.io/yuz7e/. Publications written in English, Spanish, and Portuguese were covered. Search was conducted in three stages: first, one researcher conducted data search (RCCH); then identified studies were screened based on title and abstract; finally, studies were independently assessed in full-text considering the inclusion/exclusion criteria by two researchers (RCCH and EWN) ( Figure 1 ). In the event of disagreement or conflicts between the researchers, results were discussed based on full-text evaluation until reaching consensus.

Selection of Studies

Studies were included in this review if they met the following eligibility criteria: a) targeted school-aged children and/or adolescents (6–18 years old) of Latin American countries, b) addressed an intervention for primary prevention of obesity using at least one school-based component, c) reported obesity-related outcomes, d) comprised a controlled or before-and-after design, and e) included information on intervention components and/or process. Exclusion criteria were: a) studies that included children under six years old, categorized as preschool-aged, b) targeted overweight and/or obese children/adolescents as secondary prevention or treatment, c) addressed an intervention that was not conducted in a Latin American country, and d) reported solely dietary and/or PA outcomes.

Studies were not restricted regarding duration, follow-up period, risk of obesity, and intervention implementers.

Quality Assessment

Study quality was assessed using the standardized Effective Public Health Practice Project Quality Assessment Tool (EPHPP Tool). It comprises six components ¹⁷17. Jackson N. Handbook systematic reviews of health promotion and public health interventions. London (UK): The Cochrane Collaboration; 2003. p.57-67.: a) selection bias, b) study design, c) confounders, d) blinding, e) data collection methods (validity and reliability of tools), and f) withdrawals or drop-outs per group. Two researchers (RCCH and EWN) independently assessed the collected studies. Following EPHPP guidelines, each criterion was rated as good, fair, or poor, and each study received an overall score by the sum of the six ratings. In the event of any discrepancy between researchers, each study was reassessed collectively to reach a final decision.

Data Extraction

One researcher (RCCH) extracted details on each study intervention characteristics and summarized them in a table using a narrative synthesis. Collected data consisted of: first author name; publication year; country and specific setting (region-city); intervention focus; number of participants and age; target group (low socioeconomic status [SES]); intervention activities, duration and follow-up; theoretical basis, outcome measures, process and/or cost evaluation; and overall quality evaluation. Outcome measures were considered those related to obesity (prevalence of overweight and/or obesity, BMI, BMI z-score), dietary/nutrition behavior (e.g., fruit, vegetables, fast foods, and snacks intake), and PA behavior (e.g., PA time, exercise tolerance, and endurance). Effectiveness across studies was determined by effect size (ES). The following formula, also adopted by other studies ¹⁸18. Shadish WR, Hedges LV, Pustejovsky JE. Analysis and meta-analysis of single-case designs with a standardized mean difference statistic: a primer and applications. J Sch Pyschol. 2014;52(2):123-47. https://doi.org/10.1016/j.jsp.2013.11.005
https://doi.org/10.1016/j.jsp.2013.11.00... , was used to estimate Cohen’s D ES: d = ( x ₁ – x ₂ )/ s , where x ₁ is the mean of the intervention group (IG), x ₂ the mean of the control group (CG), and s the pooled standard deviation. ES was considered trivial if < 0.2, small if equal to 0.2 or < 0.5, medium if equal to 0.5 or < 0.8, and large if equal to or higher than 0.8. For before-and-after study designs, ES was estimated based on the results of the last reported follow-up. ES values were tabulated for each outcome and based on intervention focus (whether dietary/nutrition, PA, or both).

RESULTS

Literature Search

Our initial search identified 8,273 publications on the databases and three by handsearching reference lists ( Figure 1 ). After eliminating duplicates and screening studies titles/abstracts, 133 articles remained. By reading articles full-text and applying eligibility criteria, we found 71 articles unrelated to obesity prevention, 18 describing school-based programs not conducted in Latin America, 8 including children under 6 years old (categorized as preschoolers), 9 that did not report obesity-related outcomes, and 7 that were not based on school activities, all of which were excluded. Sixteen interventions (reported in 20 publications) met the inclusion criteria and were included in the systematic review. Several Latin America countries had very few or no school-based studies on neither of the four databases.

General Characteristics of the Studies

Among the 16 interventions included in our study ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... , 5 (31%) were conducted in Mexico ²⁰20. Elizondo-Montemayor L, Gutiérrez NG, Moreno Sánchez DM, Monsiváis Rodríguez FV, Martínez U, Nieblas B, et al. Intervención para promover hábitos saludables y reducir obesidad en adolescentes de preparatoria. Estud Soc (Hermosillo, Son.). 2014;22(43):217-39. , ²⁵25. Safdie M, Jennings-Aburto N, Lévesque L, Janssen I, Campirano-Núñez F, López-Olmedo N, et al. Impact of a school-based intervention program on obesity risk factors in Mexican children. Salud Publica Mex. 2013;55 Suppl 3:374-7. https://doi.org/10.21149/spm.v55s3.5138
https://doi.org/10.21149/spm.v55s3.5138... , 4 (25%) in Chile ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
https://doi.org/10.3305/nh.2013.28.4.658... , ²³23. Ratner G R, Durán A S, Garrido L MJ, Balmaceda H S, Jadue H L, Atalah S E. Impacto de una intervención en alimentación y actividad física sobre la prevalencia de obesidad en escolares. Nutr Hosp. 2013;28(5):1508-14. https://doi.org/10.3305/nh.2013.28.5.6644
https://doi.org/10.3305/nh.2013.28.5.664... , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
https://doi.org/10.4067/S0034-9887200800... , ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
https://doi.org/10.1038/sj.ijo.0802611... , 3 in Brazil (19%) ³⁰30. Fernandes PS, Bernardo CO, Campos RMMB, Vasconcelos FAG. Evaluating the effect of nutritional education on the prevalence of overweight/obesity and on foods eaten at primary schools. J Pediatr (Rio J). 2009;85(4):315-21. https://doi.org/10.2223/JPED.1917
https://doi.org/10.2223/JPED.1917... , 3 in Peru (19%) ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... , ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. , ³⁴34. Pérez Villasante L, Raigada Mares J, Collins Estrada A, Mauricio Alza S, Felices Parodi A, Jiménez Castro S, et al. Efectividad de un programa educativo en estilos de vida saludables sobre la reducción de sobrepeso y obesidad en el Colegio Robert M. Smith; Huaraz, Ancash, Perú. Acta Med Peru. 2008;25(4):204-9. , and 1 in Argentina (6%) ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. ( Table 1 ). All studies collected data from both genders and most of them were conducted with primary school students ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... , ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. (4–14 years old), except one with high school students (14–17 years) ²⁰20. Elizondo-Montemayor L, Gutiérrez NG, Moreno Sánchez DM, Monsiváis Rodríguez FV, Martínez U, Nieblas B, et al. Intervención para promover hábitos saludables y reducir obesidad en adolescentes de preparatoria. Estud Soc (Hermosillo, Son.). 2014;22(43):217-39. and one with students from both education levels (6–16 years) ³⁴34. Pérez Villasante L, Raigada Mares J, Collins Estrada A, Mauricio Alza S, Felices Parodi A, Jiménez Castro S, et al. Efectividad de un programa educativo en estilos de vida saludables sobre la reducción de sobrepeso y obesidad en el Colegio Robert M. Smith; Huaraz, Ancash, Perú. Acta Med Peru. 2008;25(4):204-9. . Over 30% (n = 5) focused strictly on diet or nutrition ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. , ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. , ³⁰30. Fernandes PS, Bernardo CO, Campos RMMB, Vasconcelos FAG. Evaluating the effect of nutritional education on the prevalence of overweight/obesity and on foods eaten at primary schools. J Pediatr (Rio J). 2009;85(4):315-21. https://doi.org/10.2223/JPED.1917
https://doi.org/10.2223/JPED.1917... , ³¹31. Sichieri R, Trotte AP, Souza RA, Veiga GV. School randomised trial on prevention of excessive weight gain by discouraging students from drinking sodas. Public Health Nutr. 2009;12(2):197-202. https://doi.org/10.1017/S1368980008002644
https://doi.org/10.1017/S136898000800264... , ³⁶36. Ramírez-López E, Grijalva-Haro MI, Valencia ME, Ponce JA, Artalejo E. Impacto de un programa de desayunos escolares en la prevalencia de obesidad y factores de riesgo cardiovascular en niños sonorenses. Salud Publica Mex. 2005;47(2):126-33. , one on PA ³²32. Farias ES, Paula F, Carvalho WRG, Gonçalves EM, Baldin AD, Guerra-Júnior G. Influence of programmed physical activity on body composition among adolescent students. J Pediatr (Rio J). 2009;85(1):28-34. https://doi.org/10.2223/JPED.1864
https://doi.org/10.2223/JPED.1864... , ³³33. Farias ES. Efeito da atividade física programada sobre a adiposidade corporal em escolares adolescentes [tese]. Campinas, SP: Faculdade de Ciências Médicas da Unicamp; 2008. , and over 60% (n = 10) included both dietary/nutrition and PA intervention programs ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... , ²⁰20. Elizondo-Montemayor L, Gutiérrez NG, Moreno Sánchez DM, Monsiváis Rodríguez FV, Martínez U, Nieblas B, et al. Intervención para promover hábitos saludables y reducir obesidad en adolescentes de preparatoria. Estud Soc (Hermosillo, Son.). 2014;22(43):217-39. , ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
https://doi.org/10.3305/nh.2013.28.4.658... , ²³23. Ratner G R, Durán A S, Garrido L MJ, Balmaceda H S, Jadue H L, Atalah S E. Impacto de una intervención en alimentación y actividad física sobre la prevalencia de obesidad en escolares. Nutr Hosp. 2013;28(5):1508-14. https://doi.org/10.3305/nh.2013.28.5.6644
https://doi.org/10.3305/nh.2013.28.5.664... , ²⁵25. Safdie M, Jennings-Aburto N, Lévesque L, Janssen I, Campirano-Núñez F, López-Olmedo N, et al. Impact of a school-based intervention program on obesity risk factors in Mexican children. Salud Publica Mex. 2013;55 Suppl 3:374-7. https://doi.org/10.21149/spm.v55s3.5138
https://doi.org/10.21149/spm.v55s3.5138...

26. Aburto NJ, Fulton JE, Safdie M, Duque T, Bonvecchio A, Rivera JA. Effect of a school-based intervention on physical activity: cluster-randomized trial. Med Sci Sports Exerc. 2011;43(10):1898-906. https://doi.org/10.1249/MSS.0b013e318217ebec
https://doi.org/10.1249/MSS.0b013e318217...

27. Bacardí-Gascón M, Pérez-Morales ME, Jiménez-Cruz A. A six month randomized school intervention and an 18-month follow-up intervention to prevent childhood obesity in Mexican elementary schools. Nutr Hosp. 2012;27(3):755-62. https://doi.org/10.3305/nh.2012.27.3.5756
https://doi.org/10.3305/nh.2012.27.3.575...

28. Colin-Ramirez E, Castillo-Martínez L, Orea-Tejeda A, Vergara-Castaneda A, Keirns-Davis C, Villa-Romero A. Outcomes of a school-based intervention (RESCATE) to improve physical activity patterns in Mexican children aged 8-10 years. Health Educ Res. 2010;25(6):1042-9. https://doi.org/10.1093/her/cyq056
https://doi.org/10.1093/her/cyq056... - ²⁹29. Colín-Ramírez E. Actividad física y dieta para Ia prevención de factores de riesgo cardiovascular (RESCATE). Rev Esp Nutr Comunitaria. 2009;15(2):71-80. , ³⁴34. Pérez Villasante L, Raigada Mares J, Collins Estrada A, Mauricio Alza S, Felices Parodi A, Jiménez Castro S, et al. Efectividad de un programa educativo en estilos de vida saludables sobre la reducción de sobrepeso y obesidad en el Colegio Robert M. Smith; Huaraz, Ancash, Perú. Acta Med Peru. 2008;25(4):204-9. , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
https://doi.org/10.4067/S0034-9887200800... , ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
https://doi.org/10.1038/sj.ijo.0802611... . Sample size ranged from 121 to 3,086 subjects, and half of the studies (n = 8) targeted students with low SES ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
https://doi.org/10.3305/nh.2013.28.4.658... . Intervention minimum duration was four months and minimum follow-up five, whereas maximum period for both was two years. Only four studies based their intervention design and/or activities on a theoretical framework ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
https://doi.org/10.3305/nh.2013.28.4.658... , ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. , ²⁵25. Safdie M, Jennings-Aburto N, Lévesque L, Janssen I, Campirano-Núñez F, López-Olmedo N, et al. Impact of a school-based intervention program on obesity risk factors in Mexican children. Salud Publica Mex. 2013;55 Suppl 3:374-7. https://doi.org/10.21149/spm.v55s3.5138
https://doi.org/10.21149/spm.v55s3.5138... , and seven limitedly reported their process (attendance, adherence) ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... , ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. , ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
https://doi.org/10.3305/nh.2013.28.4.658... , ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. . A single study reported intervention cost evaluation ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. .

Characteristics of the Intervention

After reviewing each study specificities, we identified three intervention domains, as summarized in Table 1 , following the Health Promoting School Framework developed by the World Health Organization (WHO) ³⁸38. Langford R, Bonell CP, Jones H, Pouliou T, Murphy S, Waters E, et al. The WHO Health Promoting School framework for improving the health and well-being of students and their academic achievement. Cochrane Database Syst Rev. 2014;(4):CD008958. https://doi.orh/10.1002/14651858.CD008958.pub2
https://doi.orh/10.1002/14651858.CD00895... . The main domains entail school environment, curriculum, and partnership with families and/or the wider community. As most interventions adopted a school curriculum component, only those including at least two more domains were considered multi-component. Most interventions targeting diet alone (four out of five) were mainly educational, promoting classroom sessions encouraging healthy eating ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. , ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. , ³⁰30. Fernandes PS, Bernardo CO, Campos RMMB, Vasconcelos FAG. Evaluating the effect of nutritional education on the prevalence of overweight/obesity and on foods eaten at primary schools. J Pediatr (Rio J). 2009;85(4):315-21. https://doi.org/10.2223/JPED.1917
https://doi.org/10.2223/JPED.1917... , ³¹31. Sichieri R, Trotte AP, Souza RA, Veiga GV. School randomised trial on prevention of excessive weight gain by discouraging students from drinking sodas. Public Health Nutr. 2009;12(2):197-202. https://doi.org/10.1017/S1368980008002644
https://doi.org/10.1017/S136898000800264... , whereas the remaining one was a school breakfast program ³⁶36. Ramírez-López E, Grijalva-Haro MI, Valencia ME, Ponce JA, Artalejo E. Impacto de un programa de desayunos escolares en la prevalencia de obesidad y factores de riesgo cardiovascular en niños sonorenses. Salud Publica Mex. 2005;47(2):126-33. . Among these, one was considered multi-component for embracing efforts for environmental change along with education activities for parental involvement ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. . The intervention focused on PA compared a curriculum of PA programming with a conventional physical education (PE) class ³²32. Farias ES, Paula F, Carvalho WRG, Gonçalves EM, Baldin AD, Guerra-Júnior G. Influence of programmed physical activity on body composition among adolescent students. J Pediatr (Rio J). 2009;85(1):28-34. https://doi.org/10.2223/JPED.1864
https://doi.org/10.2223/JPED.1864... , ³³33. Farias ES. Efeito da atividade física programada sobre a adiposidade corporal em escolares adolescentes [tese]. Campinas, SP: Faculdade de Ciências Médicas da Unicamp; 2008. . Interventions targeting nutrition and PA (n = 10) implemented both educational and environmental activities ²⁰20. Elizondo-Montemayor L, Gutiérrez NG, Moreno Sánchez DM, Monsiváis Rodríguez FV, Martínez U, Nieblas B, et al. Intervención para promover hábitos saludables y reducir obesidad en adolescentes de preparatoria. Estud Soc (Hermosillo, Son.). 2014;22(43):217-39. , ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
https://doi.org/10.3305/nh.2013.28.4.658... , ²³23. Ratner G R, Durán A S, Garrido L MJ, Balmaceda H S, Jadue H L, Atalah S E. Impacto de una intervención en alimentación y actividad física sobre la prevalencia de obesidad en escolares. Nutr Hosp. 2013;28(5):1508-14. https://doi.org/10.3305/nh.2013.28.5.6644
https://doi.org/10.3305/nh.2013.28.5.664... , ²⁵25. Safdie M, Jennings-Aburto N, Lévesque L, Janssen I, Campirano-Núñez F, López-Olmedo N, et al. Impact of a school-based intervention program on obesity risk factors in Mexican children. Salud Publica Mex. 2013;55 Suppl 3:374-7. https://doi.org/10.21149/spm.v55s3.5138
https://doi.org/10.21149/spm.v55s3.5138... , ²⁶26. Aburto NJ, Fulton JE, Safdie M, Duque T, Bonvecchio A, Rivera JA. Effect of a school-based intervention on physical activity: cluster-randomized trial. Med Sci Sports Exerc. 2011;43(10):1898-906. https://doi.org/10.1249/MSS.0b013e318217ebec
https://doi.org/10.1249/MSS.0b013e318217... , and six of them were multi-component interventions that also included parental involvement ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... , ²⁷27. Bacardí-Gascón M, Pérez-Morales ME, Jiménez-Cruz A. A six month randomized school intervention and an 18-month follow-up intervention to prevent childhood obesity in Mexican elementary schools. Nutr Hosp. 2012;27(3):755-62. https://doi.org/10.3305/nh.2012.27.3.5756
https://doi.org/10.3305/nh.2012.27.3.575... , ²⁸28. Colin-Ramirez E, Castillo-Martínez L, Orea-Tejeda A, Vergara-Castaneda A, Keirns-Davis C, Villa-Romero A. Outcomes of a school-based intervention (RESCATE) to improve physical activity patterns in Mexican children aged 8-10 years. Health Educ Res. 2010;25(6):1042-9. https://doi.org/10.1093/her/cyq056
https://doi.org/10.1093/her/cyq056... , ²⁹29. Colín-Ramírez E. Actividad física y dieta para Ia prevención de factores de riesgo cardiovascular (RESCATE). Rev Esp Nutr Comunitaria. 2009;15(2):71-80. , ³⁴34. Pérez Villasante L, Raigada Mares J, Collins Estrada A, Mauricio Alza S, Felices Parodi A, Jiménez Castro S, et al. Efectividad de un programa educativo en estilos de vida saludables sobre la reducción de sobrepeso y obesidad en el Colegio Robert M. Smith; Huaraz, Ancash, Perú. Acta Med Peru. 2008;25(4):204-9. , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
https://doi.org/10.4067/S0034-9887200800... , ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
https://doi.org/10.1038/sj.ijo.0802611...

School-Based Studies Outcomes and Effect Sizes

Tables 2–4 show the effect of the interventions on every outcome: first, obesity-related (particularly the prevalence of overweight and/or obesity, BMI, and BMI z-score); and then behavioral outcomes, including PA and diet intake. Over 60% of the collected studies reported a significant effect on at least one dietary/PA or obesity-related outcome ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... . Seven studies provided the necessary data for estimating the respective effect size ²⁰20. Elizondo-Montemayor L, Gutiérrez NG, Moreno Sánchez DM, Monsiváis Rodríguez FV, Martínez U, Nieblas B, et al. Intervención para promover hábitos saludables y reducir obesidad en adolescentes de preparatoria. Estud Soc (Hermosillo, Son.). 2014;22(43):217-39. , two were randomized controlled trials ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. , ³¹31. Sichieri R, Trotte AP, Souza RA, Veiga GV. School randomised trial on prevention of excessive weight gain by discouraging students from drinking sodas. Public Health Nutr. 2009;12(2):197-202. https://doi.org/10.1017/S1368980008002644
https://doi.org/10.1017/S136898000800264... , three were non-randomized controlled trials ³²32. Farias ES, Paula F, Carvalho WRG, Gonçalves EM, Baldin AD, Guerra-Júnior G. Influence of programmed physical activity on body composition among adolescent students. J Pediatr (Rio J). 2009;85(1):28-34. https://doi.org/10.2223/JPED.1864
https://doi.org/10.2223/JPED.1864... , ³³33. Farias ES. Efeito da atividade física programada sobre a adiposidade corporal em escolares adolescentes [tese]. Campinas, SP: Faculdade de Ciências Médicas da Unicamp; 2008. , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
https://doi.org/10.4067/S0034-9887200800... , ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
https://doi.org/10.1038/sj.ijo.0802611... , two were quasi-experimental studies with a pretest-posttest nonequivalent groups design ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... , ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. , and three were before-and-after studies ²⁰20. Elizondo-Montemayor L, Gutiérrez NG, Moreno Sánchez DM, Monsiváis Rodríguez FV, Martínez U, Nieblas B, et al. Intervención para promover hábitos saludables y reducir obesidad en adolescentes de preparatoria. Estud Soc (Hermosillo, Son.). 2014;22(43):217-39. , ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
https://doi.org/10.3305/nh.2013.28.4.658... , ²⁷27. Bacardí-Gascón M, Pérez-Morales ME, Jiménez-Cruz A. A six month randomized school intervention and an 18-month follow-up intervention to prevent childhood obesity in Mexican elementary schools. Nutr Hosp. 2012;27(3):755-62. https://doi.org/10.3305/nh.2012.27.3.5756
https://doi.org/10.3305/nh.2012.27.3.575... . Most studies showed a weak overall quality (n = 13) ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... , whereas three showed moderate ²⁷27. Bacardí-Gascón M, Pérez-Morales ME, Jiménez-Cruz A. A six month randomized school intervention and an 18-month follow-up intervention to prevent childhood obesity in Mexican elementary schools. Nutr Hosp. 2012;27(3):755-62. https://doi.org/10.3305/nh.2012.27.3.5756
https://doi.org/10.3305/nh.2012.27.3.575... , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
https://doi.org/10.4067/S0034-9887200800... , ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
https://doi.org/10.1038/sj.ijo.0802611... . Most common limitations were regarding blinding (16 studies), confounders (11 studies), and unclear validity of data collection methods (8 studies).

Obesity-related outcomes

1. Prevalence of overweight and/or obesity: few studies reported this outcome (n = 3) ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
   https://doi.org/10.4067/S0034-9887200800... , ³⁶36. Ramírez-López E, Grijalva-Haro MI, Valencia ME, Ponce JA, Artalejo E. Impacto de un programa de desayunos escolares en la prevalencia de obesidad y factores de riesgo cardiovascular en niños sonorenses. Salud Publica Mex. 2005;47(2):126-33. . Two multi-component interventions significantly decreased the prevalence of overweight and/or obesity on -9.5 to -3.5 percentage points ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
   https://doi.org/10.4067/S0034-9887200800... (Table 2); no positive ES was reported.

2. BMI: seven studies reported changes in BMI, three of which found a statistically significant intervention effect ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
   https://doi.org/10.4067/S0034-9887200800... , ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
   https://doi.org/10.1038/sj.ijo.0802611... (Table 2). Among interventions targeting diet alone, one study reported a positive effect on BMI z-score and a trivial ES for the entire sample (-0.12) ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. . The intervention targeting PA achieved no significant effect ³²32. Farias ES, Paula F, Carvalho WRG, Gonçalves EM, Baldin AD, Guerra-Júnior G. Influence of programmed physical activity on body composition among adolescent students. J Pediatr (Rio J). 2009;85(1):28-34. https://doi.org/10.2223/JPED.1864
   https://doi.org/10.2223/JPED.1864... , ³³33. Farias ES. Efeito da atividade física programada sobre a adiposidade corporal em escolares adolescentes [tese]. Campinas, SP: Faculdade de Ciências Médicas da Unicamp; 2008. . As for interventions targeting both diet and PA, two studies reported significant effects on BMI or BMI z-score – one for the overall sample (girls -0.15, boys -0.19) ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
   https://doi.org/10.4067/S0034-9887200800... and one for boys only (BMI 0.09, BMI z-score 0.06) ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
   https://doi.org/10.1038/sj.ijo.0802611... . All aforementioned studies comprised multi-component interventions, including parental educational activities on nutrition.

Behavioral outcomes

1. PA: four studies consisted of dietary and PA interventions. The study focused on PA reported and recorded significant effects on physical condition tests and/or PA time ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
   https://doi.org/10.3305/nh.2013.28.4.658... , ²⁷27. Bacardí-Gascón M, Pérez-Morales ME, Jiménez-Cruz A. A six month randomized school intervention and an 18-month follow-up intervention to prevent childhood obesity in Mexican elementary schools. Nutr Hosp. 2012;27(3):755-62. https://doi.org/10.3305/nh.2012.27.3.5756
   https://doi.org/10.3305/nh.2012.27.3.575... , ³³33. Farias ES. Efeito da atividade física programada sobre a adiposidade corporal em escolares adolescentes [tese]. Campinas, SP: Faculdade de Ciências Médicas da Unicamp; 2008. , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
   https://doi.org/10.4067/S0034-9887200800... , ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
   https://doi.org/10.1038/sj.ijo.0802611... (Table 3): all participants improved their performance on two of the three tests reported by Farias (2008), with ES ranging from small to large (0.43-1.22). However, only the boy subgroup improved their performance on the sit and reach test ³³33. Farias ES. Efeito da atividade física programada sobre a adiposidade corporal em escolares adolescentes [tese]. Campinas, SP: Faculdade de Ciências Médicas da Unicamp; 2008. . Regarding studies addressing the two interventions, one reported a small positive ES (0.31-0.47) ²⁷27. Bacardí-Gascón M, Pérez-Morales ME, Jiménez-Cruz A. A six month randomized school intervention and an 18-month follow-up intervention to prevent childhood obesity in Mexican elementary schools. Nutr Hosp. 2012;27(3):755-62. https://doi.org/10.3305/nh.2012.27.3.5756
   https://doi.org/10.3305/nh.2012.27.3.575... on PA time while the others successfully achieved ES ranging from small to medium when reporting on physical condition tests – two of which in the overall sample (0.23 – 0.55) ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
   https://doi.org/10.3305/nh.2013.28.4.658... , ³3. Shama-Levy T, Cuevas-Nasu L, Gaona-Pineda EB, Gomez-Acosta LM, Morales-Ruan MDC, Hernandez-Avila M, et al. Sobrepeso y obesidad en niños y adolescentes en México, actualización de la Encuesta Nacional de Salud y Nutrición de Medio Camino 2016. Salud Publica Mex. 2018;60(3):244-53. https://doi.org/10.21149/8815
   https://doi.org/10.21149/8815... ⁷7. Cullen KW, Hartstein J, Reynolds KD, Vu M, Resnicow K, Greene N, White MA. Improving the school food environment: results from a pilot study in middle schools. J Am Diet Assoc. 2007;107(3):484-9. https://doi.org/10.1016/j.jada.2006.12.004
   https://doi.org/10.1016/j.jada.2006.12.0... and one among boys (ES 0.73) ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
   https://doi.org/10.4067/S0034-9887200800... .

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   Table 3
   Outcome change and effect size in physical activity for school-based studies reporting a significance level (n = 5).

2. Diet: five studies recorded positive effects on one or several dietary behaviors (two targeting diet-only and three diet and PA) ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
   https://doi.org/10.17843/rpmesp.2017.343... , ²⁰20. Elizondo-Montemayor L, Gutiérrez NG, Moreno Sánchez DM, Monsiváis Rodríguez FV, Martínez U, Nieblas B, et al. Intervención para promover hábitos saludables y reducir obesidad en adolescentes de preparatoria. Estud Soc (Hermosillo, Son.). 2014;22(43):217-39. , ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. , ²⁷27. Bacardí-Gascón M, Pérez-Morales ME, Jiménez-Cruz A. A six month randomized school intervention and an 18-month follow-up intervention to prevent childhood obesity in Mexican elementary schools. Nutr Hosp. 2012;27(3):755-62. https://doi.org/10.3305/nh.2012.27.3.5756
   https://doi.org/10.3305/nh.2012.27.3.575... , ³¹31. Sichieri R, Trotte AP, Souza RA, Veiga GV. School randomised trial on prevention of excessive weight gain by discouraging students from drinking sodas. Public Health Nutr. 2009;12(2):197-202. https://doi.org/10.1017/S1368980008002644
   https://doi.org/10.1017/S136898000800264... . However, we managed to estimate ES for only two of the interventions targeting both domains (Table 4). One intervention targeting diet alone reported a one-percentage point increase in the daily intake of two healthy food (orange juice and skim milk) among girls and a significant decrease in the consumption of hamburger and hotdog among both boys and girls ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. . As for interventions targeting both domains, one managed to sustain fruits intake in the IG (≥ 5 days/week), but reported a significant decrease in the CG (-10.3%). Whereas IG also showed an increasing water intake (+6.1%), in CG it decreased similarly to fruits (-10.6%) ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
   https://doi.org/10.17843/rpmesp.2017.343... . The two remaining studies reported a trivial and a small positive ES on similar behaviors (ranging from 0.11 to 0.29) ²⁰20. Elizondo-Montemayor L, Gutiérrez NG, Moreno Sánchez DM, Monsiváis Rodríguez FV, Martínez U, Nieblas B, et al. Intervención para promover hábitos saludables y reducir obesidad en adolescentes de preparatoria. Estud Soc (Hermosillo, Son.). 2014;22(43):217-39. , ²⁷27. Bacardí-Gascón M, Pérez-Morales ME, Jiménez-Cruz A. A six month randomized school intervention and an 18-month follow-up intervention to prevent childhood obesity in Mexican elementary schools. Nutr Hosp. 2012;27(3):755-62. https://doi.org/10.3305/nh.2012.27.3.5756
   https://doi.org/10.3305/nh.2012.27.3.575... .

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   Table 4
   Outcome change and effect size in diet or nutrition for school-based studies reporting a significance level (n = 5).

DISCUSSION

Among the 16 studies that met inclusion criteria and were included in our systematic review, 10 (60%) achieved significant positive effects on at least one of their reported outcomes. Of these, three interventions focused on diet, one on PA, and six on both PA and diet. Within the three diet-only interventions, two reported an improvement in dietary behaviors, but failed in positively impacting an obesity-related outcome ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. , ³¹31. Sichieri R, Trotte AP, Souza RA, Veiga GV. School randomised trial on prevention of excessive weight gain by discouraging students from drinking sodas. Public Health Nutr. 2009;12(2):197-202. https://doi.org/10.1017/S1368980008002644
https://doi.org/10.1017/S136898000800264... , and one reduced both of its reported obesity-related outcomes (prevalence of overweight and obesity) by reducing BMI z-score in IG ²¹21. Gago J, Rosas O, Huayna M, Jiménez D, Córdova F, Navarro A, et al. Efectividad de una intervención multisectorial en educación alimentaria nutricional para prevenir y controlar el sobrepeso y la obesidad en escolares de cuatro instituciones educativas públicas del distrito de Villa El Salvador. Rev Peru Epidemiol. 2014;18(3):e04. . The PA-only intervention managed to improve PA performance within the overall sample for most tests, but this effect had no significantly impact on any obesity-related outcome ³³33. Farias ES. Efeito da atividade física programada sobre a adiposidade corporal em escolares adolescentes [tese]. Campinas, SP: Faculdade de Ciências Médicas da Unicamp; 2008. . Of the six diet/PA-focused interventions, three managed to improve a single behavioral outcome ¹⁹19. Aparco JP, Bautista-Olórtegui W, Pillaca J. Evaluación del impacto de la intervención educativa-motivacional “Como Jugando” para prevenir la obesidad en escolares del Cercado de Lima: resultados al primer año. Rev Peru Med Exp Salud Publica. 2017;34(3):386-94. https://doi.org/10.17843/rpmesp.2017.343.2472
https://doi.org/10.17843/rpmesp.2017.343... , ²⁰20. Elizondo-Montemayor L, Gutiérrez NG, Moreno Sánchez DM, Monsiváis Rodríguez FV, Martínez U, Nieblas B, et al. Intervención para promover hábitos saludables y reducir obesidad en adolescentes de preparatoria. Estud Soc (Hermosillo, Son.). 2014;22(43):217-39. , ²²22. Lobos Fernández LL, Leyton Dinamarca B, Kain Bercovich J, Vio del Río F. Evaluación de una intervención educativa para la prevención de la obesidad infantil en escuelas básicas de Chile. Nutr Hosp. 2013;28(4):1156-64. https://doi.org/10.3305/nh.2013.28.4.6588
https://doi.org/10.3305/nh.2013.28.4.658... , one positively affected both diet and PA, and two impacted both behavioral and obesity-related outcomes (one PA+ BMI; one PA+ BMI+ obesity prevalence) ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
https://doi.org/10.4067/S0034-9887200800... , ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
https://doi.org/10.1038/sj.ijo.0802611... .

Considering these results, we identified evidence-based effectiveness in three obesity prevention interventions conducted in Latin America that targeted promoting healthy diet and PA by associating environmental, educational, and parental involvement activities (multi-component), corroborating other international reviews ¹²12. Verstraeten R, Roberfroid D, Lachat C, Leroy JL, Holdsworth M, Maes L, et al. Effectiveness of preventive school-based obesity interventions in low-and middle-income countries: a systematic review. Am J Clin Nutr. 2012;96(2):415-38. https://doi.org/10.3945/ajcn.112.035378
https://doi.org/10.3945/ajcn.112.035378... , ³⁹39. Van Cauwenberghe E, Maes L, Spittaels H, Lenthe FJ, Brug J, Oppert JM, et al. Effectiveness of school-based interventions in Europe to promote healthy nutrition in children and adolescents: systematic review of published and ”grey” literature. Br J Nutr. 2010;103(6):781-97. https://doi.org/10.1017/S0007114509993370
https://doi.org/10.1017/S000711450999337... , ⁴⁰40. Wang D, Stewart D. The implementation and effectiveness of school-based nutrition promotion programmes using a health-promoting schools approach: a systematic review. Public Health Nutr. 2013;16(6):1082-100. https://doi.org/10.1017/S1368980012003497
https://doi.org/10.1017/S136898001200349... . Although these interventions ES often range from trivial to small, they have a significant capability of providing benefits if scaled to a greater level.

The results of two interventions implemented in Chile and one in Mexico were strengthened based on these studies, showing the best methodological quality (moderate) among our sample ²⁷27. Bacardí-Gascón M, Pérez-Morales ME, Jiménez-Cruz A. A six month randomized school intervention and an 18-month follow-up intervention to prevent childhood obesity in Mexican elementary schools. Nutr Hosp. 2012;27(3):755-62. https://doi.org/10.3305/nh.2012.27.3.5756
https://doi.org/10.3305/nh.2012.27.3.575... , ³⁵35. Kain B J, Uauy D R, Leyton D B, Cerda K R, Olivares C S, Vio D F. Efectividad de una intervención en educación alimentaria y actividad física para prevenir obesidad en escolares de la ciudad de Casablanca, Chile (2003-2004). Rev Med Chil. 2008;136(1):22-30. https://doi.org/10.4067/S0034-98872008000100003
https://doi.org/10.4067/S0034-9887200800... , ³⁷37. Kain J, Uauy D R, Vio F, Cerda R, Leyton B. School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study. Int J Obes. 2004;28(4):483-93. https://doi.org/10.1038/sj.ijo.0802611
https://doi.org/10.1038/sj.ijo.0802611... . However, this data also stress the weakness within this research field in Latin America – as already reported by prior studies ⁴¹41. Herscovici CR, Kovalskys I. Childhood obesity: a review of school-based preventive interventions. Rev Mex Trastor Aliment. 2015;6(2):143-51. https://doi.org/10.1016/j.rmta.2015.10.006
https://doi.org/10.1016/j.rmta.2015.10.0... , ⁴²42. Pérez-Morales ME, Bacardí-Gascón M, Jiménez-Cruz A, Armendáriz-Anguiano A. Intervenciones aleatorias controladas basadas en las escuelas para prevenir la obesidad infantil: revisión sistemática de 2006 a 2009. Arch Latinoam Nutr. 2009;59(3):253-9. – regarding the amount and methodological quality of publications. Our systematic review found studies conducted in only 5 of the 20 countries in the region (25% representation) to meet inclusion criteria, and most of them presented a poor methodological quality.

Parental involvement has been considered of key influence for improving children’s lifestyle behaviors and preventing obesity. Our findings emphasize the importance of their role within the school setting, corroborating other reviews worldwide ¹⁰10. Sharma M. International school-based interventions for preventing obesity in children. Obes Rev. 2007;8(2):155-67. https://doi.org/10.1111/j.1467-789X.2006.00268.x
https://doi.org/10.1111/j.1467-789X.2006... , ⁴³43. Kruk JJ, Kortekaas F, Lucas C, Jager-Wittenaar H. Obesity: a systematic review on parental involvement in long-term European childhood weight control interventions with a nutritional focus. Obes Rev. 2013;14(9):745-60. https://doi.org/10.1111/obr.12046
https://doi.org/10.1111/obr.12046... , which may also be explained by the culture of family tradition in Latin America ¹⁰10. Sharma M. International school-based interventions for preventing obesity in children. Obes Rev. 2007;8(2):155-67. https://doi.org/10.1111/j.1467-789X.2006.00268.x
https://doi.org/10.1111/j.1467-789X.2006... .

The potential influence of age in intervention effects is an ongoing debate. While some studies argue that programs targeting older students tend to achieve better outcomes ¹¹11. Budd GM, Volpe SL. School-based obesity prevention: research, challenges, and recommendations. J Sch Health. 2006;76(10):485-95. https://doi.org/10.1111/j.1746-1561.2006.00149.x
https://doi.org/10.1111/j.1746-1561.2006... , ⁴⁴44. Stice E, Shaw H, Marti CN. A meta-analytic review of obesity prevention programs for children and adolescents: the skinny on interventions that work. Pyschol Bull. 2006;132(5):667-91. https://doi.org/10.1037/0033-2909.132.5.667
https://doi.org/10.1037/0033-2909.132.5.... , other meta-analysis found younger children (elementary school students, aged 4–9 years) to experience greater BMI effects than middle (10–13 years) and high school students (14 years or older) ⁴⁵45. Cook-Cottone C, Casey CM, Freely TH, Baran J. A meta-analytic review of obesity prevention in the schools: 1997-2008. Psychol Sch. 2009;46(8):695-719. https://doi.org/10.1002/pits.20409
https://doi.org/10.1002/pits.20409... . However, regional and national disparities in education systems should be regarded when comparing and interpreting results based on age. In Latin America, the education system is characterized by three basic levels: pre-school, primary school, and high school, which, in most countries, entails students aged approximately 3–5 years, 6–13 years, and 13–18 years ⁴⁶46. Garcia da Rosa S, Guadalupe C, Ruiz-Pozuelo J. The Latin America learning barometer: moving forward in access, lagging behind in learning. Washington, DC: Global Economy and Development at Brookings; 2015 [cited 2019 Jul 12]. (Working Paper, 93). Available from: https://www.brookings.edu/wp-content/uploads/2015/11/WorkingPaper93Web_NOV.pdf
https://www.brookings.edu/wp-content/upl... , ⁴⁷47. Bellei C, coordinador. Situación educativa de América Latina y el Caribe: Hacia la educación de calidad para todos al 2015. Santiago (CHL): Oficina Regional de Educación para América Latina y el Caribe-UNESCO; 2013 [cited 2019 Jul 17]. Available from: http://www.unesco.org/new/fileadmin/MULTIMEDIA/FIELD/Santiago/images/SITIED-espanol.pdf
http://www.unesco.org/new/fileadmin/MULT... , respectively. In our review, thirteen studies targeted primary school students, ranging from 7.6 to 10.9 years old (an average of 9.09 years). We suggest further studies to approach both children and adolescents, enabling a deeper understanding regarding age impact on intervention outcomes.

The greater improvement on boys’ physical condition after interventions, reported in two studies, were previously discussed ⁴⁸48. Trost SG, Pate RR, Sallis JF, Freedson PS, Taylor WC, Dowda M, et al. Age and gender differences in objectively measured physical activity in youth. Med Sci Sports Exerc.2002;34(2):350-5. https://doi.org/10.1097/00005768-200202000-0002
https://doi.org/10.1097/00005768-2002020... , ⁴⁹49. Kropski JA, Keckley PH, Jensen GL. School-based obesity prevention programs: an evidence-based review. Obesity (Silver Spring). 2008;16(5):1009-18. https://doi.org/10.1038/oby.2008.29
https://doi.org/10.1038/oby.2008.29... . Considering these findings, it seems that boys tend to engage in more vigorous activity than girls, who tend to be less active ⁹9. De Bourdeaudhuij I, Van Cauwenberghe E, Spittaels H, Oppert JM, Rostami C, Brug J, et al. School-based interventions promoting both physical activity and healthy eating in Europe: a systematic review within the HOPE project. Obes Rev. 2011;12(3):205-16. https://doi.org/10.1111/j.1467-789X.2009.00711.x
https://doi.org/10.1111/j.1467-789X.2009... . One study found a greater improvement in dietary intake among girls ²⁴24. Herscovici CR, Kovalskys I, De Gregorio MJ. Gender differences and a school-based obesity prevention program in Argentina: a randomized trial. Rev Panam Salud Publica. 2013;34(2):75-82. . Such differences may be explained by the intervention focus, which did not address PA specifically, but rather educational components grounded on social learning theory, to which Kropski et al. (2008) suggest girls might respond better. Yet, further research are required for a better discernment of gender differences within PA and dietary intake behaviors.

Intervention duration and its association with effectiveness are still an ongoing debate, as well as an agreed differentiation cut-off. Bautista-Castano et al. (2004) found that interventions lasting between 6 months and one year are more effective (triceps skin-fold and BMI anthropometrics) than shorter and longer-term interventions ⁵⁰50. Bautista-Castaño I, Doreste J, Serra-Majem L. Effectiveness of interventions in the prevention of childhood obesity. Eur J Epidemiol. 2004;19(7):617-22. https://doi.org/10.1023/b:ejep.0000036890.72029.7c
https://doi.org/10.1023/b:ejep.000003689... . Another meta-analysis found short-term interventions (0 to 12 weeks) to have negative effects on BMI, whereas longer interventions (13 weeks or more) are associated with small, significant, and positive BMI effects ⁴⁵45. Cook-Cottone C, Casey CM, Freely TH, Baran J. A meta-analytic review of obesity prevention in the schools: 1997-2008. Psychol Sch. 2009;46(8):695-719. https://doi.org/10.1002/pits.20409
https://doi.org/10.1002/pits.20409... . The duration of the three effective interventions identified in our systematic review ranged from 6 to 11 months, within the cutoff suggested by the aforementioned reviews. Besides duration, follow-up period may also be important for identifying intervention sustained benefits. However, these data are often disregarded in the literature, which might be justified by the difficulty in assessing effects of groups no longer under the intervention arm.

Around 40% of the studies reported evaluation process mostly regarding the overall percentage of individuals targeted by the intervention (students, parents, and teachers) who participated or attended nutrition or PA sessions, that is: the percentages of adherence or attendance. Yet, various researchers argue the need of a throughout evaluation of the implementation process to better contextualize and assess the program true effect ⁵¹51. Meij JS, Wal MF, Mechelen W, Chinapaw MJM. A mixed methods process evaluation of the implementation of JUMP-in, a multilevel school-based intervention aimed at physical activity promotion. Health Promot Pract. 2013;14(5):777-90. https://doi.org/10.1177/1524839912465750
https://doi.org/10.1177/1524839912465750... , ⁵²52. Carroll C, Patterson M, Wood S, Booth A, Rick J, Balain S. A conceptual framework for implementation fidelity. Implement Sci. 2007;2(1):40. https://doi.org/10.1186/1748-5908-2-40
https://doi.org/10.1186/1748-5908-2-40... . Such need is even sharper in complex or multi-component interventions ⁵³53. Hasson H. Systematic evaluation of implementation fidelity of complex interventions in health and social care. Implement Sci. 2010;5:67. https://doi.org/10.1186/1748-5908-5-67
https://doi.org/10.1186/1748-5908-5-67... that are not solely based on education. Considering that, we recommend further study to employ both qualitative and quantitative approaches by a mixed-method design, to better plan, correct, and evaluate interventions and their affecting factors.

Our systematic review pose some limitations. First, comparing and interpreting effect sizes from heterogeneous studies targeting children and adolescents is always challenging, and only a few studies provided the appropriate pediatric measures of obesity-related outcomes (BMI z-scores). Second, many methodological deficiencies identified by the quality assessment instrument owed to lack of information, so we urge studies to provide more detailed information regarding the adopted methods. Third, we considered intervention effects regardless of the evaluation data process, because these results were not thoughtfully reported. As our focus was obesity-related outcomes, we might have potentially excluded studies addressing nutrition and PA behaviors as primary outcomes that also contributed to obesity prevention, not only by weight loss.

CONCLUSIONS

We found evidence of the effectiveness of three school-based interventions for preventing obesity among school-aged children and adolescents in Latin America. These interventions were characterized as moderate quality, included the multi-components of health education, school environment, and parental involvement focusing on healthy eating and PA behaviors, and had better study designs, few execution limitations, and a 6-month minimum duration. Future efforts on preventing obesity in Latin American countries should consider evidence-based preventions experiences, such as those identified in our review, as guides. They should also consider gender differences, appropriate duration, and mixed-method evaluation designs combining both quantitative and qualitative approaches, as their association could provide a clearer and deeper understanding of the school-based interventions true effect.

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