Evaluation of a 4-month Online Lifestyle Intervention on the BMI Z-score of Mexican School Children During COVID-19 Pandemic: Randomized Controlled Pilot Trial
Phase: NA
Conditions: Childhood Obesity
Sponsor: Universidad de Sonora

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Date: 10/06/2021 
Official Title: 
“ Evaluation of a 4-month Online Lifestyle Intervention on the BMI Z-score of Mexican 
School Children During COVID-19 Pandemic: Randomized Controlled Pilot Trial” 
 
NCT: 
NCT04772859 
 
Study Protocol Available1: Ramírez-Rivera DL, Martínez-Contreras R, Ruelas AL, 
Henry-Mejía G, Quizán-Plata T,Esparza-Romero J, Haby MM, Díaz-Zavala RG. 
Efecto de una intervención en línea de cambio en el estilo de vida sobre el puntaje 
zIMC de escolares mexicanos: protocolo de ensayo controlado aleatorizado piloto 
cegado a evaluadores durante la pandemia por COVID-19. Rev Esp Nutr Hum Diet. 
2021; 25 (Supl. 2): e1320. doi: 10.14306/renhyd.25.S2.1320 
 
 
ABSTRACT 
 
Introduction: School closures due to the COVID-19 pandemic represent a risk 
factor for the development of childhood obesity, due to the increase in unhealthy 
behaviors. Online lifestyle interventions in schoolchildren could help to mitigate this 
problem. However, to our knowledge, no randomized controlled trials have been 
conducted to prevent obesity in schoolchildren during COVID-19. The aim of this 
study is to evaluate the effect of a 4-month online lifestyle intervention on the BMI Z-
score of Mexican schoolchildren during the COVID-19 pandemic in an intervention 
group compared to a control group. Material and Methods: This is a protocol for an 
outcome assessor-blinded pilot randomized controlled trial. Schoolchildren from a 
public elementary school in Hermosillo, Sonora, Mexico will be invited to participate. 
Participants will be randomized to an intervention group (online lifestyle intervention) 
or a control group. The intervention will include online sessions of nutrition education 
and physical activity (60 minutes per session, 30 minutes for nutrition education and 

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30 minutes for physical activity) and nutrition information for parents. The control 
group will receive a digital brochure with nutrition recommendations at the beginning 
of the study and access to the program materials at the end of the study. The 
measurements will be performed at baseline and at 4 months. The primary outcome 
will be the BMI Z- score. Secondary outcomes: waist circumference, body fat 
percentage, nutrition knowledge, lifestyle parameters, participation, retention and 
acceptance of the intervention. The changes on the outcomes will be analyzed using 
an intention to treat analysis. The protocol was approved by the Research Ethics 
Committee of the University of Sonora Nursing Department and registered in Clinical 
Trials. Conclusion: To our knowledge, the study will provide the first evidence of 
the evaluation of online interventions for the prevention of obesity in schoolchildren 
derived from a randomized controlled trial, which could be crucial in the fight against 
childhood obesity. 
 
INTRODUCTION 
 
At the beginning of the year 2020, the World Health Organization declared the start 
of the COVID-19 pandemic. This is an infectious disease caused by the SARS-CoV-
2 virus, which can cause mild symptoms to severe respiratory disease.2 One of the 
strategies to mitigate infections has been social distancing and home confinement.3 
This, among other consequences, has caused the closure of schools in different 
countries, affecting millions of students in the world.4 In Latin American and 
Caribbean countries, at the beginning of the pandemic it was reported that 95% of 
schools were closed due to COVID-19, affecting 156 million students of all levels.5 
The schools closure can have consequences on the education and lifestyle of 
children and adolescents.6 It has been seen that when children are not in school 
(unstructured days), they gain more weight, compared to school days. 7,8 This, due 
to an increase in the adoption of unhealthy behaviors, such as physical inactivity, 
more screen time, irregular sleep patterns and a high consumption of ultra-
processed foods.9 Similarly, during the COVID-19 lockdown, unhealthy behaviors in 

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children have been reported. In a study with children and adolescents from Italy, it 
was found that during confinement they increased an average of 4.85 h/day in front 
of the screen and 0.65 h/day of sleep. On the other hand, the time of physical activity 
decreased by 2.35 h/week.10 In another study carried out in different countries in 
Europe and Latin America, it was found that children and adolescents increased their 
consumption of sweet beverages and fried and sweet foods, during confinement.11 
This is concerning, because about 340 million children and adolescents worldwide 
are overweight.12 In Mexico, 35.5% of schoolchildren have overweight or obesity 13, 
and this has both short- and long-term health consequences.14,15 
Different agencies have proposed lines of action to prevent child malnutrition during 
the pandemic. One of them is about the implementation of behavior change 
strategies to promote healthy eating and physical activity in children, using mass 
communication or technological resources.16 
One option for providing health interventions is through the use of digital media. The 
“eHealth” consists of the use of Information and Communication Technologies (ICT) 
to promote health.17 The internet is one of the most used technologies by children 
and adolescents. It has been estimated that one in three children around the world 
uses the Internet for different entertainment and learning activities.18,19 This provides 
the opportunity to use interactive communication methods for the prevention of 
childhood obesity through the promotion of healthy behaviors.20 
Hamel & Robbins carried out a systematic review, of 15 studies of web based 
programs with children and adolescents with different change behavior theories 
frameworks. It was found that most of these programs were effective in modifying 
healthy eating behaviors such as: increased consumption of fruits, vegetables, and 
decreased calories and fat. Likewise, positive results in BMI and % body fat.21 

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These types of online interventions could represent a key strategy to prevent the 
development of childhood obesity during the current global health crisis. To our 
knowledge, to date there is no randomized clinical trial evaluating this type of 
program during the COVID-19 pandemic. 
The present research group previously developed and evaluated a lifestyle change 
program focused on obesity prevention in Mexican schoolchildren in a face-to-face 
format, where positive results were obtained.22 Given the current situation due to 
COVID-19, this program was adapted to an online format to evaluate its effect 
through a pilot randomized controlled trial. 
Explanation for the choice of comparators 
The control group will be of children from the same public school as the children in 
the intervention group. The risk of contamination is reduced by not having face-to-
face classes, but it is not completely eliminated, since there may be participants who 
take classes in the same group and interact online. Even so, the results will be valid 
if significant differences between groups are observed, as we observed in a previous 
study, because the previous situation would reduce the effect of the intervention. 
OBJECTIVES 
Primary objective 
 
• To evaluate the effect of an online lifestyle intervention on the BMI Z-score 
of Mexican schoolchildren at 4 months during the COVID-19 pandemic in 
the intervention group compared to a control group. 
 
Secondary objectives 
• To evaluate the effect of an online lifestyle change intervention on waist 
circumference, body fat, physical activity and sedentary behaviors, food 
consumption, nutrition knowledge and quality of life of Mexican schoolchildren 
at 4 months during the COVID-19 pandemic in the intervention group 
compared to a control group. 

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• To evaluate the effect of an online lifestyle intervention on the retention, 
participation and acceptance of Mexican schoolchildren at 4 months during 
the COVID-19 pandemic in the intervention group. 
 
 
MATERIAL AND METHODS 
 
Study desgin 
This is a pilot randomized controlled trial blinded to assessors, with 4-month follow-
up. It is a pilot study, because it we want to evaluate the effect and feasibility of the 
online intervention, to later carry out a definitive study considering an adequate 
sample size. The study will consist of two parallel arms, of superiority and with 1:1 
allocation ratio. 
To carry out this protocol, the SPIRIT 2013 guidewas followed.23. The protocol was 
approved by the Research Ethics Committee of the Nursind Department of the 
University of Sonora (CEI-ENFERMERIA-EPM-003-2020) and registered on the 
Clinical.trials.gov platform (NCT04772859). 
Participants 
Children from a public elementary school in Hermosillo, Sonora will be invited to 
participate in the study. It is worth mentioning that this public school is not 
representative of all the schools in Hermosillo, Sonora. Hermosillo is a city of about 
884,273 inhabitants and around of 392 public elementary schools. It is located in the 
state of Sonora, in northwestern Mexico. Because the program is entirely online, 
students who agree to participate will take the intervention from home. 
 
 
 

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Sample size 
No studies of online lifestyle interventions to prevent obesity in schoolchildren during 
the pandemic were found to obtain the effect size and standard deviation needed to 
estimate the study sample size. So, we decided that it would be a pilot study of at 
least 50 participants and no more than 70. This was decided considering our 
logistical capacity, which implies measuring the response variables at home in a 
period of 2 weeks, in addition to being able to provide intervention, among other 
things. The invitation will be made to all students from fourth to sixth grade of a public 
school in Hermosillo Sonora. 
Eligibility criteria 
Sign the consent and informed assent and complete the anthropometric 
measurements and lifestyle questionnaires. 
Inclusion criteria 
• 4th, 5th and 6th grade students from the participating elementary school. 
• Have access to the internet. 
•  Have an electronic device (eg computer, laptop, tablet or smartphone). 
• Nutritional status: normal weight, overweight or obesity. 
Exlusion criteria 
• Have a medical condition that affects body weight. 
• Taking medication that affects body weight. 
• Take another intervention that affects body weight. 
• Have a condition that prevents physical activity. 
• Withdraw informed consent or assent. 
• Have a sibling participating in the study. 
Implementers 
The lifestyle intervention will be implemented by a Nutritionist and two interns from 
the Bachelor's Degree in Physical Culture and Sports from the study team. In 

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addition, there will be the support of interns from the Nutritional Sciences Bachelor 
of the University of Sonora.  
Interventions of the study 
Online lifestyle intervention 
The intervention will be based on the "Planet Nutrition" program. This program has 
a handbook that was previously developed by our study group and includes nutrition, 
physical activity, health, and behavior change strategies (Table.1). The program will 
last 4 months (March to July 2021). The components of the program will be: online 
nutrition education sessions, physical activity and family participation. It is worth 
mentioning that the nutrition education and physical activity sessions will be offered 
in the same 1-hour class. The first 30 minutes will be for nutrition education and the 
remaining 30 minutes for physical activity or games that involve movement. 
Sessions   Topics 
1 
Creating healthy habits 
2 
What is excess weight? 
3 
Is it really bad to eat ultra-processed 
food? 
4 
The bitter truth of sweetened 
beverages 
5 
The importance of physical activity 
6 
Sedentary behaviors 
7 
Food Guidelines: My plate  
8 
Analyzing my healthy lunch 
9 
Jar for healthy drinking  
10 
Sweetened beverages vs healthy 
lunch 
11 
Reading food labels  
12 
Importance of healthy nutrition 
13 
Ultra-processed food 

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14 
Sustainable lifestyle 
15       
Traditional Mexican diet 
16 
Healthy lunch 
17 
Identifying good and bad fats 
18 
What is important to know about 
sodium? 
19 
Smoking 
20 
Learning about Cancer 
21 
Importance of consuming fruits and 
vegetables 
22 
Vitamins and minerals 
23 
Why is fiber consumption important 
24 
Gut microbiota 
25 
Jeopardy: Let's put into practice the 
learning 
26 
How to prepare a salad 
27 
Learning to prepare healthy desserts 
28 
How to be active in summer holidays 
29 
Healthy nutrition in summer holidays 
30 
Balance christmas 
31 
Planet Nutrition challenge 
 
 
 
 
Nutritional education sessions: Classes will be 3 days a week for 30 minutes 
each. Live sessions will be provided through the Zoom application, which is a 
platform for video conferencing. A code and password will be provided to access the 
private meeting. In addition, a web page of the study team (www.salud-
nutricional.com) will be used to upload the topics that are seen in classes and 
activities for the participants. Presentations based on the “Planeta Nutrition” program 
handbook will be used. In addition, depending on the session, videos and 

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infographics will be made. In each class it is intended to take a little time to play a 
game, dynamic or workshop to reinforce learning. 
The program will center on establishing health-related goals such as increasing 
consumption of fruits and vegetables, increasing physical activity time, decreasing 
hours spent in front of a screen, and reducing consumption of sweetened beverages. 
The program also will include the use of self-monitoring and positive reinforcement. 
Physical activity sessions: Classes will be implemented 3 days a week for 30 
minutes each. Children will work on developing different skills such as: flexibility, 
strength, elasticity and resistance. The Zoom digital platform will be used for the 
online (live) sessions. The classes will be recorded, in case the children want to do 
a class later. 
Parent’s participation: Parents who agree to participate in the program will be 
given a user to access a web page (www.salud-nutricional.com), where children's 
activities will be uploaded. This will be used to upload nutrition information, parenting 
activities, and study questionnaires. A private Facebook group will be created to 
upload teaching material (videos, infographics, messages and images) on a weekly 
basis. The difference between using the website and Facebook is that on the page 
the participants will be able to have the information ordered, upload their activities 
and study questionnaires. The topics addressed each week will be the same as 
those seen with the children in the nutrition sessions. On Facebook, they will have 
spaces for comments, questions, feedback and social support. 
Control group: The control group will receive general nutrition recommendations at 
the beginning of the program, based on the Nutrition and Physical Activity Guidelines 
in the Context of Overweight and Obesity in Mexican Population.24 A digital brochure 
will be sent in online format to the mail or through the WhatsApp application to 
parents. Upon completion of the study, they will be offered access to the materials 
from all the onlie lifestyle sessions, as well as physical activity videos for children 
recorded by the physical activity team. 
 
 

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Outcomes 
The primary outcome is the change of the BMI Z-score from baseline to 4 months 
between the intervention group and the control group. The change in BMI Z-score 
for each individual will be obtained by subtracting the BMI Z-score value at 4 months 
minus the baseline value. The difference between groups will be obtained by 
subtracting the mean of the change in the intervention group minus that of the 
control. 
Secondary outcomes will include the differences in waist circumference, body fat 
and relative fat mass, physical activity and sedentary lifestyle, quality of life, 
participation, attendance and nutrition knowledge. The categorical variables such 
as: food consumption and acceptance, will be evaluated with differences in 
proportions. 
Recruitment 
To invite the participants, school directors will first be contacted to invite them, inform 
them about the objectives and activities of the intervention. Fourth, fifth and sixth 
grade students from a public elementary school in Hermosillo, Sonora, Mexico will 
be invited to participate. It will seek to have a space in the students' online school 
classes, where parents will be invited to attend. A small presentation will be made 
with the invitation, objectives and activities of the intervention. During the same 
meeting, they will be sent via chat the link to a web page where they can find the the 
consent and informed assent and a personal data questionnaire to evaluate inclusion 
and exclusion criteria. They must be read and signed by parents and children online. 
Children may participate, even if the parents decide not to get involved in their part 
of the intervention. 
Randomization 
The measurements of the study will be carried out in a period of 2 weeks. Once the 
measurements are completed, the participants who meet the inclusion/exclusion 
criteria will be randomized to one of two groups: the “online lifestyle intervention” 
group or the control group. An independent person of the recruitment and 

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intervention of the study will receive a database, only with the codes and the basic 
variables of the study (BMI Z-score, sex and age) to perform the allocation of the 
participants. This will be based on a random block sequence, stratified by BMI Z-
score and sex, with an allocation ratio of 1:1. The random number sequence will be 
generated using the randomization software available on the website: 
https://randomizer.org/. Since the assignment will be made in a single moment and 
without the knowledge of the participants, its concealment will be guaranteed. 
Participants will be explicitly informed to the assigned group. 
 
Outcome measures 
Study measurements will be performed at baseline and at 4 months. The primary 
outcome (BMI Z-score), waist circumference and triceps skinfold, will be measured 
by a person blinded to the allocation group and trained in the measurement of these 
variables. These anthropometric measurements will be carried out at the 
participants' homes in an outdoor area. Hygiene measures and recommendations 
will be followed to reduce the risks of contagion (use of NK95 face masks, plastic 
face shield, surgical suit, gloves, etc. short exposure time and disinfection of 
materials). Measurements will be made in less than 15 minutes. Before the home 
visit, a questionnaire will be sent to screen for possible symptoms related to COVID-
19. Lifestyle questionnaires will be conducted online. 
Primary outcome 
• BMI Z-score: The measurement will be obtained using the sex, age, weight 
(kg) and height (m) of the participants.The height and weight will be combined 
(kg/m2) to obtain the BMI Z- score,  expressed in units of standard deviation. 
Using The WHO Anthro Plus software.25 
Secondary outcomes 
• Weight: To obtain the weight (kg), a TANITA SC-240 will be used. The 
measurement will be used to obtain the BMI Z-score.26 

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• Height: The SECA 213 stadiometer will be used, following the Frankfurt plan. 
This measure will be used to obtain the BMI Z-score.26 
• Waist circumference: A Lufkin metallic anthropometric tape will be used. 
The umbilical scar will be taken as reference.26 
• Body fat: It will be estimated with the measurement of the tricipital skinfold, 
using a formula validated for Mexican children. To take the tricipital skinfold, 
the ISAK methodology will be followed.27,28  
• Relative fat mass: This is an estimator of total body fat. A formula carried out 
with children (8-14 years) will be used where the data of waist circumference 
(cm), height and sex (0 boys and 1 girls) will be needed.29 
• Nutrition knowledge: A questionnaire designed by the study team will be 
used to assess knowledge on nutrition. It consists of 32 questions on nutrition 
and health. 
• Food consumption: Some questions from the semi-quantitative food 
frequency questionnaire from the National Health and Nutrition Survey were 
used.30 We asked about the frequency of consumption of ultra-processed 
foods (sweet beverages, fried foods, cakes and cookies) and healthy foods 
(fruits, vegetables and water) in the previous 7 days. For each food, the size 
of the portion consumed was asked, considering an average portion 
established in the FFQ. 
• Physical activity and sedentary activities: The physical activity and 
sedentary lifestyle part of the questionnaire “The Health Behavior in School-
aged Children” (HBSC) was used, which is a validated lifestyle questionnaire 
for school-age children.31 It consists of 9 questions, 5 questions related to the 
time and frequency of physical activity and 4 to sedentary activities. 
• Nutrition knowledge: a questionnaire designed by the research team (not 
validated) was used to assess the knowledge on nutrition and health. It 
consists of 32 questions with multiple choice answers. The results were 
evaluated on a scale from 0 to 10, the more correct answers, the greater 
score. 

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• Quality of life: The PedsQL™ (Pediatric Quality of Life Inventory) 
questionnaire was used, which was designed to assess quality of life aspects 
in both healthy pediatric patients (2 to 18 years old) and those with chronic 
diseases. The questionnaire consists of 23 questions about physical, 
emotional, social and school functioning. The responses are on a 5-point likert 
scale (never = 0 to always = 4). The score for each item is reversed and 
transformed to a linear scale of 0–100, with a higher score indicating a better 
quality of life.32 
• Retention: It will be evaluated with the percentage of participants 
(intervention and control group) who complete the intervention and the 
measurements at 4 months. 
• Participation or attendance of schoolchildren:  It will be evaluated with the 
percentage of attended intervention sessions and with the percentage of 
participants who attended all sessions. 
• Parent’s participation: At the end of the study, parents will be asked through 
an online questionnaire, the number of materials consulted from the program 
and will be reported as a percentage. 
• Acceptance. Acceptability will be obtained with a questionnaire applied to 
children and parents to qualify the intervention, materials and benefits 
obtained with the intervention. 
• Personal information. The first step for the screening of the participants 
consists of an online questionnaire of personal data. This will be sent at the 
time of the invitation to the program. Personal data of the child, internet 
access and electronic device, if they have a disease, if they take medications 
or perform extra interventions that may affect body weight will be asked. In 
addition, the email and education leve lof the parents will be asked. 
 
Withdrawal of participants 
Participants may withdraw from the study at any time they wish, being able to 
inform the reason or not. 

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Statistical Analysis 
The normality of the data will be evaluated with the Shapiro Wilk test. Data will 
be presented as mean and standard deviation (mean ± SD) or median and 
interquartile ranges according to their distribution. An independent samples t-test 
or Mann-Whitney U test will be used to analyze the difference in BMI Z-score and 
changes in secondary outcomes between groups. A chi-square test will be used 
to make comparisons on categorical variables. Two-tailed tests with p ≤ 0.05 will 
be used as the criterion for statistical significance.  
Data will be analyzed with an intention-to-treat analysis. If participants decide to 
withdraw from the intervention, they will be asked if the measurement at 4 months 
can be obtained to have at least the primary outcome for inclusion in the 
intention-to-treat analysis. If data is not obtained for any reason or subjects were 
excluded due to a protocol violation, they will be replaced by their baseline 
measurement. 
 Results will focus on change in the primary study variable (BMI Z-score), while 
changes in secondary variables and sub-analyses (sex and BMI: normal, 
overweight/obese) will be considered exploratory only. For data analysis, NCSS 
version 10 software (Number Cruncher Statistical System for Windows, 
Kaysville, UT, USA) will be used. 
Confidentiality 
Identifiable information and will be kept confidential. Each participant will be 
assigned a code, therefore, their identifiable information will appear with that 
code and not with names. Only the physical files will keep the names, which will 
be kept by the principal investigator of the study, in a safe place. Only the study 
team may have access to the database, for their purposes. 
Declaration of interest 
The authors did not report any potential conflicts of interest. 
 

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