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The obesity pandemic has now reached children, and households should change their lifestyles to prevent it.
The objective was to assess the effect of a comprehensive intervention on body mass index
A yearlong study was conducted at 4 elementary schools in Mexico City. Intervention group (IG) and control group (CG) were split equally between governmental and private schools. Three educational in-person parents and children sessions were held at 2-month intervals to promote healthy eating habits and exercise. To reinforce the information, a website provided extensive discussion on a new topic every 2 weeks, including school snack menus and tools to calculate body mass index in children and adults. Text messages were sent to parents’ mobile phones reinforcing the information provided. The IG contained 226 children and CG 181 children. We measured their weight and height and calculated BMIZ at 0, 6, and 12 months.
The CG children showed a change of +0.06 (95% CI 0.01, 0.11) and +0.05 (95% CI 0.01, 0.10) in their BMIZ at 6 and 12 months, respectively. The BMIZ of IG children decreased by -0.13 (95% CI -0.19 to -0.06) and -0.10 (95% CI -0.16 to -0.03), respectively, and the effect was greater in children with obesity.
The comprehensive intervention tested had beneficial effects, preserved the BMIZ of normal weight children, and reduced the BMIZ of children with obesity.
Childhood obesity is a public health problem because it is associated with comorbidities such as metabolic syndrome, hypertriglyceridemia, and type 2 diabetes [
Metabolically, obesity is caused by an imbalance in which energy intake exceeds expenditure in a persistent fashion. Low energy expenditure is caused by decreased physical activity and increased sedentary habits [
Studies in children and adolescents have shown that Web-based information improves people’s knowledge, attitudes, and behaviors related to feeding and physical activity [
The aim of this study was to compare the daily nutrition-based activities performed in schools in Mexico City, such as the availability of healthy food and drinking water [
The study was approved by Research, Ethics, and Biosafety Committees of the Federico Gomez Children’s Hospital of Mexico (HIMFG in Spanish), a National Institute of Health. After the Ministry of Public Education granted the authorization to perform the study, 4 elementary schools from a middle-class suburb of Mexico City with similar number of students were included in the study. All school principals granted authorization for the study. The intervention was implemented in 2 schools, 1 governmental and 1 private (intervention group, IG), whereas the other 2 schools, 1 governmental and 1 private, were controls (control group, CG). Before implementation, educational materials and the website were designed and developed, which were the tools of the intervention. The subsequent activities are described as phase 1 of the study. The grades that participated were the first to fourth. Boys and girls were included, regardless of their BMIZ. Before starting the study, both objectives and activities were explained to teachers, parents, and children and also verbal agreement and written informed consent was obtained from children and their parents, respectively.
The artworks for this project, such as images of children eating healthy foods, were created by the designers of Universum, the Science Museum of the National Autonomous University of Mexico (UNAM). Designs were considered to be ad hoc for the age of the children and culture of Mexico City.
Twenty topics were developed to inform parents about overweight, obesity, healthy eating, physical activity, and health risks that obesity involves, which are described in
Various materials were developed for the children to take home, such as laminated place mats with the images of the Mexican Eatwell Plate [
Guidelines for parents were developed with information on how to prepare a healthy school lunch, including numerous examples.
Study population: screening results and follow-up.
Work topics on the website, phone messages, and posters.
Website topics | Messages | Poster |
1. What is obesity? Why are there more obese people now than before? | M1, M2 | The change in lifestyle has affected our health |
2. Obesity and its relationship to chronic degenerative diseases | M3, M4 | |
3. Lifestyles, feeding, activity/sedentary, and health monitoring with regular measurements | M5, M6 | Consequences of overweight and obesity in health |
4. Lifestyle and health. We stay as we are or we make an effort to improve the health of the family and of each of its members | M7, M8 | |
5. Eating breakfast and bringing lunch to school are essential for health and school performance of children | M9, M10 | Breakfast at home and lunch at school |
6. Physical activity is much more than expending energy | M11, M12 | |
7. Sedentary lifestyle, a risk for health | M13, M14 | Free and spontaneous play |
8. Measure yourself. Self-measurement is much more than knowing your weight | M15, M16 | |
9. Plain water is the healthiest | M17, M18 | How can we avoid a sedentary lifestyle? |
10. Not all the energy that we consume is the same in terms of health | M19, M20 | |
11. Carbohydrates. Health benefits and risks | M21, M22 | Natural water is the healthiest drink |
12. Fiber. Health benefits and risks | M23, M24 | |
13. Importance of eating fruits and vegetables | M25, M26 | Fruits and vegetables in my feeding |
14. Lipids. Health benefits and risks | M27, M28 | |
15. Proteins in food. Health benefits and risks | M29, M30 | Varied feeding |
16. Table salt in food. Health benefits and risks | M31, M32 | |
17. Vitamins and minerals. Health benefits and risks | M33, M34 | Natural foods better than processed foods |
18. Family behavior during food consumption at home | M35, M36 | |
19. Planning food purchases. Learning to read labels on processed and industrialized foods | M37, M38 | |
20. Integration. Create a healthy eating environment with your family | M39, M40 |
The project website was nested in the official HIMFG website www.himfg.edu.mx. The picture of 2 children eating healthy foods was the identification icon of the project. Upon accessing the site, the user found the biweekly highlighted topic and the following icons:
1. Previous topics. By accessing this icon, the list of biweekly topics appeared, which could be accessed at any time. At the end of 2 weeks, the current theme was stored in this folder.
2. School snacks. This icon contained information on how to develop a healthy school snack and 25 examples of school snacks.
3. Guidelines on healthy eating and physical activity. This icon contained files of 2 guides on nutrition and physical activity; these printed guides were also sent to parents through their children.
4. Posters. This folder contained the posters hung at schools on a monthly basis. Each poster reinforced the current theme. A total of 9 posters were placed.
5. Software for the calculation and interpretation of body mass index (BMI). This icon invited parents to assess the BMI of themselves and their children. When they entered a weight and height, the program returned a BMI, indicating whether there was a health risk.
6. Contact, questions, and comments. In this section, parents could contact researchers to raise questions or make comments related to the project.
7. Window for researchers. The page included a window that allowed researchers to activate the user, evaluate the number of accesses to the site by each of the families, read the comments or questions that were raised by parents, and keep the page updated with the information of each of the icons. A visual of the website is shown in
The intervention was implemented from October 2013 to July 2014; parents and all children, regardless of their BMIZ, participated in the intervention.
Information about the socioeconomic status was obtained by administering a questionnaire to know the number of children, parental education, and housing characteristics.
Weight, height, and waist circumference were measured in schoolchildren of all schools at baseline and then at 6 and 12 months. Weight was measured with a digital scale (Seca 882; Seca Corp, Hamburg, Germany) with an accuracy of 0.1 kg. Height was measured with a stadiometer (Seca 225; Seca Corp, Hamburg, Germany) with an accuracy of 0.1 cm. Waist circumference was measured with a nonelastic flexible measuring tape (Seca 200). Two trained nutritionists took these measurements according to international procedures [
Body mass index (BMI) and BMI
Children were classified according to the nutritional status as underweight (
After each of the anthropometric measurements, both groups of children were handed a letter with the results of the nutritional status and tips to maintain or improve their health. The recommendations mainly focused on eating and physical activity habits.
Descriptive statistics were used to describe the baseline of the study population. The mean weight and height were adjusted for age and sex by multiple linear regression. The socioeconomic variable was built with the information obtained from the questionnaire on housing characteristics and ownership of property. Households were grouped into tertiles according to their score for socioeconomic status. To compare the groups at baseline,
Because, frequently in this type of study, participants do not always follow instructions and consequently adherence is never 100%, we considered it appropriate to perform the data analysis by intention-to-treat, in which all participants assigned to each group are analyzed regardless of their adherence.
The intragroup BMIZ changes from baseline to 6 months and from baseline to 12 months were compared using paired
A model of mixed-effects linear regression was used to assess the change in BMIZ during follow-up. Because children are nested within schools, a mixed model with 3 levels and random intercepts by subject and school were tested. The model was adjusted by the fixed variables of age and BMIZ at baseline. The interaction between the intervention group and the time at each evaluation, 6 and 12 months, was assessed. Mean BMIZ by group (intervention or control) and by time was calculated and a graphic was done using marginal analysis.
The number of schoolchildren who participated was 226 in the IG and 181 in the CG. The participation rates were 55.2% (226/409) in IG and 44.4% (181/408) in CG. At 12 months, 85% of children in both groups completed the measurements. The proportion of children who did not conclude the study can be attributed to children moving to different schools for personal reasons. However, there was no movement of children between study groups (
The development of the intervention is presented in
Intervention development during the school year (n=226).
Intervention |
n (%) | |||
None | 110 (48.7) | |||
At least one session | 116 (51.3) | |||
1 session | 78 (34.5) | |||
2 sessions | 34 (15.0) | |||
3 sessions | 4 (1.8) | |||
No | 134 (59.3) | |||
Yes | 92 (40.7) | |||
No message | 20 (8.8) | |||
Message | 206 (91.2) |
Baseline characteristics of the study population according to study group.
Characteristics |
Control |
Intervention |
||||||||
8.1 (1.2) | 7.9 (1.2) | .13 | ||||||||
90 (49.7) | 101 (44.7) | .31 | ||||||||
Weightb, kg, mean (SD) | 30.1 (5.1) | 29.3 (5.0) | .13 | |||||||
Heightb, cm, mean (SD) | 127.4 (7.5) | 126.4 (7.4) | .14 | |||||||
BMIc |
0.98 (1.3) | 0.85 (1.4) | .35 | |||||||
BMI classificationd, n (%) | ||||||||||
Normal (-2≤ | 89 (49.2) | 129 (57.1) | ||||||||
Overweight (1≤ |
46 (25.4) | 52 (23.0) | ||||||||
Obese ( |
45 (25.4) | 45 (19.9) | .25 | |||||||
Waist circumference, percentile, mean (SD) | 53.0 (21.8) | 52.2 (21.2) | .69 | |||||||
Secondary or less | 24 (14.1) | 42 (20.8) | ||||||||
High school or technical school | 77 (45.3) | 76 (37.6) | ||||||||
College career or postgraduate | 69 (40.6) | 84 (41.6) | .16 | |||||||
1-2 | 116 (72.1) | 153 (76.1) | ||||||||
≥3 | 45 (27.9) | 48 (23.9) | .38 | |||||||
Lower | 42 (26.1) | 63 (32.1) | ||||||||
Medium | 53 (32.9) | 76 (38.8) | ||||||||
Higher | 66 (41.0) | 57 (29.1) | .06 | |||||||
At home | 129 (86.6) | 141 (82.9) | .37 | |||||||
On the mobile phone | 94 (63.0) | 92 (54.1) | .11 | |||||||
Mothers | 146 (85.4) | 190 (92.2) | .03 | |||||||
Parents | 155 (90.1) | 201 (95.3) | .05 | |||||||
a
b Means adjusted by age and sex.
c BMI: body mass index.
d World Health Organization, 2007.
When comparing the BMIZ change between IG and CG in children who started the study with normal weight, differences observed between groups at 6 and 12 months were -0.17 (95% CI -0.27 to -0.07) and -0.12 (95% CI -0.24 to -0.01), respectively. In children who were overweight at baseline, an effect between groups of -0.15 (95% CI -0.24 to -0.01) at 6 months was observed, although this effect was not maintained at 12 months. In obese children, the effect on BMIZ between groups was -0.12 (95% CI -0.23 to -0.02) at 6 months and -0.16 (95% CI -0.32 to -0.01) at 12 months.
Intra- and intergroup body mass index
Characteristics |
0 months | 6 months | 12 months | ∆ 0 to 6 months | ∆ 0 to 12 months | |||||
Mean (SD) | Mean (SD) | Mean (SD) | Mean (95% CI) | Mean (95% CI) | ||||||
Control | 18.4 (3.2) | 18.8 (3.3) | 19.1 (3.5) | 0.50 (0.38 to 0.60) | <.001 | 0.77 (0.62 to 0.92) | <.001 | |||
Intervention | 17.9 (3.3) | 18.0 (3.4) | 18.4 (3.6) | 0.13 (0.03 to 0.23) | .01 | 0.50 (0.36 to 0.63) | <.001 | |||
Control | 1.01 (1.3) | 1.08 (1.3) | 1.06 (1.3) | 0.07 (0.02 to 0.12) | .004 | 0.05 (-0.01 to 0.11) | .07 | |||
Intervention | 0.85 (1.3) | 0.77 (1.3) | 0.80 (1.3) | -0.07 (-0.12 to -0.03) | .002 | -0.05 (-0.10 to 0.01) | .08 | |||
Normal weight | ||||||||||
Control | -0.15 (0.7) | -0.01 (0.8) | -0.05 (0.8) | 0.13 (0.05 to 0.21) | .002 | 0.10 (0.01 to 0.19) | .04 | |||
Intervention | -0.13 (0.7) | -0.17 (0.7) | -0.16 (0.8) | -0.04 (-0.10 to 0.02) | .20 | -0.02 (-0.10 to 0.05) | .46 | |||
Difference IGe versus CGf | -0.17 (-0.27 to -0.07) | <.001 | -0.12 (-0.24 to -0.01) | .03 | ||||||
Overweight | ||||||||||
Control | 1.43 (0.3) | 1.52 (0.4) | 1.52 (0.5) | 0.09 (-0.01 to 0.18) | .07 | 0.09 (-0.03 to 0.21) | .15 | |||
Intervention | 1.52 (0.3) | 1.46 (0.4) | 1.56 (0.4) | -0.06 (-0.16 to 0.03) | .20 | 0.05 (-0.06 to 0.15) | .36 | |||
Difference IG versus CG | -0.15 (-0.24 to -0.01) | .03 | -0.04 (-0.20 to 0.11) | .59 | ||||||
Obesity | ||||||||||
Control | 2.64 (0.5) | 2.60 (0.5) | 2.58 (0.5) | -0.05 (-0.11 to 0.02) | .14 | -0.06 (-0.15 to 0.04) | .22 | |||
Intervention | 2.78 (0.6) | 2.61 (0.7) | 2.55 (0.7) | -0.17 (-0.26 to -0.08) | <.001 | -0.22 (-0.35 to -0.09) | .001 | |||
Difference IG versus CG | -0.12 (-0.23 to -0.02) | .02 | -0.16 (-0.32 to -0.01) | .04 |
a Paired
b BMI: body mass index.
c BMIZ: body mass index
d World Health Organization, 2007.
e IG: intervention group.
f CG: control group.
On the basis of a linear regression model with random intercept mixed effect and adjusted by baseline age and BMIZ, the graph shown in
Body mass index
This study shows the results of an intervention implemented in elementary schools comprising multiple components. The intervention included in-person and remote activities aimed at parents and children. Comparing the BMIZ during the study with the BMIZ at baseline, in the intervention group BMIZ decreased and in the control group, BMIZ increased. In addition, the intervention maintains the BMIZ of normal weight children and decreased the BMIZ of obese children. Moreover, it is pertinent to emphasize that the strategy described in this report was not intended to treat obesity but sought to reach as many parents as possible to promote changes in the eating and physical activity habits of their children regardless of BMIZ.
For the management of obese adolescents and adults, the effectiveness of sending information electronically versus individual face-to-face consultation has been compared, and weight reduction is greater in those receiving individual consultation [
In this report, when the effect was analyzed by subgroups considering the initial BMIZ, the intervention had a differential effect: the BMIZ of IG children with normal weight was maintained during the follow-up, whereas BMIZ of children from the CG increased. The obese children from the IG reduced 0.22 of BMIZ by 12 months; this effect was greater than that observed in obese children of the CG (-0.06) and the whole population of the intervention group (-0.10). These results are similar to those of a Chilean intervention study that found that obese schoolchildren are the subpopulation with better responses [
In our study, in the children with overweight in the intervention group the BMIZ decreased at 6 months (intervention effect) but this effect disappeared at 12 months; this may be because the parents of these children do not yet perceive the health problem in which their children are immersed, and returned to their usual habits.
In the IG, the greatest reduction of BMIZ was observed in the first 6 months but did not continue to decrease at 12 months. However, in the subgroup of obese children the BMIZ continued improving after 6 months. This effect has been reported in other study that used a website to send information to parents [
Concerning obese children of the CG who maintained their BMIZ (rather than increasing it), we propose that parents could have changed to healthier habits after receiving a letter with interpretation of their children’s anthropometric measurements and health care recommendations. It has been reported that regular anthropometric measures can improve or reduce BMI [
Regardless of the specific intervention, it seems that a crucial element of our strategy was that it targeted parents, who play a central role in promoting healthy habits within the family [
In our study, the parents of 91.2% (206/226) of IG children received text messages, the highest coverage of all the activities of the strategy. Each of the phone messages summarizes a topic that was extensively explained on the website. The use of mobile phones could play an important role in making successful interventions because other studies have found stronger communication effects using text messages versus the Internet [
The main limitations arise in our study: (1) The assignment of participating schools was not randomized. Despite this problem, the BMIZ of the schoolchildren of the IG and CG were comparable at baseline and the effect of the intervention was assessed with the BMIZ change (Δ) during the course of the study. (2) The study participation was approximately 50% and the reasons for nonparticipation should be explored in future studies. Nevertheless, parents of the 2 groups who agreed to participate remained in the study in relatively high proportion at 12 months. (3) The changes in dietary intake and physical activity of participants are not included in this report, and we can only assume that the changes in BMIZ of children were due to the improvement of these habits. (4) The effect of each of the components on BMIZ modification was not evaluated separately in this study because neither in-person activities nor the website consultation showed 100% parental participation. However, the positive effect observed in both normal weight children and obese children of IG possibly is due to the intervention.
The following are the strengths of this study: (1) The study sent information to parents by several channels, in person, through children, via the Internet, and via mobile phones. The few in-person sessions allowed parents a more efficient use of their time in a large, complex city in which in-person meetings are difficult. (2) The follow-up lasted 12 months, longer than in other studies in which interventions last only a few months. (3) Although the intervention had multiple components, it was affordable. (4) The intervention was not only addressed to the obese population but also involved schoolchildren of all BMI classes. This allowed us to determine that, although the effect of the intervention was greater in children with obesity, children with normal weight maintained their BMI, indicating that exposure to obesity risk factors could be decreased with this type of intervention.
Fighting overweight and obesity is a complex undertaking, and some intervention studies in schools have shown effectiveness in restraining but not reducing obesity [
Although the results of this study cannot be generalized, the intervention is promising for implementation of strategies at a distance. Sending information via the Web and smarter mobile phones could encourage better eating and physical activity habits with the aim of preserving or improving children’s BMI. In large cities where mobility is difficult but the use of the aforementioned devices has increased [
Lastly, serious and accessible information to promote healthy habits at home, which comes from the school itself, supported by a health institution such as HIMFG, always will be a counterbalance to the commercial information given by the media.
The comprehensive intervention combining in-person activities with Web-based information and mobile phone messaging maintained the BMIZ of normal weight children and decreased the BMIZ of children with obesity. Thus, this can be an affordable alternative to promote health changes in children at the household level.
Selected screenshots of the materials used in the intervention.
Selected screenshot of the website.
Selected screenshots of examples of messages sent to parents' mobile phone.
body mass index
body mass index
control group
intervention group
Federico Gomez Children’s Hospital of Mexico
National Autonomous University of Mexico
This work was supported by the Hospital Infantil de México Federico Gómez: Fondos Federales HIM/2013/003. We express our gratitude to UNAM Universum Science Museum, for the artwork for this project and for allowing schoolchildren to visit the “Life in Balance” hall. We acknowledge to physicians, nutritionists, nurses and physical educators who participated in the study writing the topics used in the Website; also, we acknowledge to children, parents, principals, and elementary schools personnel for their participation in the study. This study is part of the doctoral work of Jenny Vilchis Gil within the Program Master and Doctor of Medicine, Dentistry and Health Science, Faculty of Medicine, National Autonomous University of Mexico.
JVG participated in the design and coordination of the study as well as supervision of the fieldwork and conducting the statistical analysis. MKK participated in the design and coordination of the study and critically revised the manuscript. XD participated in conducting the statistical analysis. SFH participated in the conception and design of the research question and provided critical comments on the manuscript. All authors were involved in drafting the manuscript. All of them read and approved the final version of the manuscript.
None declared.