Gender differences and a school-based obesity prevention program in Argentina: A randomized trial

Abstract

To evaluate the impact of a school-based obesity prevention program that seeks to change food intake among students at schools in Rosario, Argentina.
This was a prospective study involving 405 children 9-11 years of age at six schools in the poor areas of Rosario, Argentina, in May-October 2008. After matching for socioeconomic status, schools were selected by simple randomization; participants were assessed at baseline (T1) and again 6 months later, after completion of the intervention (T2). The program focused on increasing the children's knowledge of healthy nutrition and exercise through four workshops; educating the parents/caregivers; and offering healthy options at the school snack bar. The main outcome measures were the children's intake of healthy and unhealthy foods (assessed with a weekly food frequency questionnaire) and their body mass index (BMI).
Of the 387 children assessed at T1, 369 were reassessed at T2 (205 intervention; 164 control). Girls at the schools where the intervention occurred increased their intake of three of the five healthy food items promoted by the program (fruits, vegetables, low-sugar cereals). Statistical significance was reached for skim milk (P = 0.03) and for pure orange juice (P = 0.05). Boys of both the intervention and control groups failed to improve their intake of healthy foods, but those of the intervention arm significantly reduced their intake of hamburgers and hot dogs (P = 0.001).
Girls were more amenable to improving their dietary intake. Overall, the program was more likely to increase consumption of healthy food than to decrease intake of unhealthy foods. Gender differences should be taken into account when designing preventive interventions.

Full text

Rev Panam Salud Publica 34(2), 2013 75
Gender differences and a school-based
obesity prevention program in Argentina:
a randomized trial
Cecile Rausch Herscovici,1 Irina Kovalskys,1
and María José De Gregorio2
During the past 30 years, childhood
obesity rates have increased sharply, not
only in developed, but also in develop-
ing countries (1). Long-term follow-up
studies suggest that overweight children
and adolescents may be at increased risk
of becoming obese adults. This is of great
concern because obesity and its related
comorbidities (e.g., type 2 diabetes, hy-
pertension, heart disease, some types of
cancer) are one of the main preventable
causes of death. In fact, the Pan American
Health Organization (PAHO) has recog-
nized that currently, the prevention of
this multifactorial condition is one of the
most important public health challenges
(2). There is evidence that a high intake
of sweetened beverages and high-fat/
high-sugar foods, coupled with a low
intake of fruits and vegetables and in-
creased sedentary behavior, is associ-
ated with obesity (3–8). Shifts in diet
and physical activity patterns have af-
fected the low- and moderate-income
Objective. To evaluate the impact of a school-based obesity prevention program
that seeks to change food intake among students at schools in Rosario, Argentina.
Methods. This was a prospective study involving 405 children 9–11 years of age
at six schools in the poor areas of Rosario, Argentina, in May–October 2008. After
matching for socioeconomic status, schools were selected by simple randomization;
participants were assessed at baseline (T1) and again 6 months later, after completion
of the intervention (T2). The program focused on increasing the children’s knowledge
of healthy nutrition and exercise through four workshops; educating the parents/
caregivers; and offering healthy options at the school snack bar. The main outcome
measures were the children’s intake of healthy and unhealthy foods (assessed with a
weekly food frequency questionnaire) and their body mass index (BMI).
Results. Of the 387 children assessed at T1, 369 were reassessed at T2 (205 interven-
tion; 164 control). Girls at the schools where the intervention occurred increased their
intake of three of the five healthy food items promoted by the program (fruits, vege-
tables, low-sugar cereals). Statistical significance was reached for skim milk (P = 0.03)
and for pure orange juice (P = 0.05). Boys of both the intervention and control groups
failed to improve their intake of healthy foods, but those of the intervention arm sig-
nificantly reduced their intake of hamburgers and hot dogs (P = 0.001).
Conclusions. Girls were more amenable to improving their dietary intake. Over-
all, the program was more likely to increase consumption of healthy food than to
decrease intake of unhealthy foods. Gender differences should be taken into account
when designing preventive interventions.
Obesity; primary prevention; child health; child nutrition; food; Argentina.
abstract
Key words
Investigación original / Original research
Rausch Herscovici C, 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.
Suggested citation
1 Obesity, Nutrition, and Physical Activity Commit-
tee, International Life Sciences Institute, Buenos
Aires, Argentina. Send correspondence to Cecile
Rausch Herscovici, email: cecilerh@gmail.com
2 Statistics Department, University of Buenos Aires,
Buenos Aires, Argentina.

76 Rev Panam Salud Publica 34(2), 2013
Original research
Rausch Herscovici et al. • Gender and school-based obesity prevention in Argentina
developing countries over the last two
decades (9). Childhood obesity in Ar-
gentina is a major public health problem
as documented by a recent study in
which 27.9% of middle- and low-income
children 10–11 years of age were over-
weight (10). Sedentary behavior and an
excess of calories seem to be part of
this multifactorial problem. Therefore,
educating families and school environ-
ments to promote healthier food choices
is critical (11). In fact, schools are a piv-
otal component of the social milieu that
shapes children’s eating and physical
activity patterns, and there is evidence
that school-based programs may affect
how youngsters perceive the influence of
dietary practices on overall health (12).
Preventive programs aimed at reduc-
ing the risk of obesity in developed and
developing countries are current pub-
lic health priorities. Educating school
children in healthy nutrition has been
signaled as one of the most effective
strategies for overcoming malnutrition
and diet-related diseases (13). Reviews
of population-based interventions car-
ried out in both school and family set-
tings with children from kindergarten
to high school mostly in the United
States and the United Kingdom indicate
that school-based interventions often re-
sult in some improvement of health
knowledge and health-related behav-
iors; additionally, the short-term effect
on nutritional state seems to be more
pronounced among girls than boys (14,
15). There is evidence that families of
middle- and upper-socioeconomic sta-
tus, as well as intact original families
(not divorced, separated, or blended)
benefit more from these programs, and
that prevention among obese children
is most successful when they are treated
together with their parents (14). To date,
interventions aimed at improving food
intake among middle school children
have had limited success in attaining di-
etary changes (16, 17). Variations across
these studies in relation to strategy (envi-
ronmental, plus policy changes), setting
(the United States), duration (2 years),
focus, and other methodological issues,
hinder the possibility of drawing general
conclusions about the value of preven-
tive measures.
Nonetheless, the best way to assess the
impact of a program and consider future
directions for allocating resources is by
evaluating the program under controlled
conditions. To date, relatively few con-
trolled studies have been published on
the prevention of overweight and obe-
sity in children and adolescents world-
wide. Worth mentioning is the scarcity
of controlled studies on obesity preven-
tion programs in developing countries
(18). Partly because assessments of inter-
ventions are too expensive for local re-
search organizations, there has been no
data published (to the authors’ knowl-
edge) on this topic regarding Argen-
tina, despite the increased prevalence of
overweight and obesity in this country
during recent years (19).
In the city of Rosario, Argentina, the
Ministry of Public Health developed and
implemented an obesity prevention in-
tervention called, “Cantinas Saludables”
(Healthy Snack Bars; HSB). This school-
based program focuses on increasing
the number of healthy options available
at the school snack bars, improving the
students’ knowledge of healthy eating,
and promoting physical activity during
school hours. Additionally, it aims to
improve parents’ knowledge of healthy
habits. In spite of being put into action
more than six years ago, the program has
never been evaluated.
The goal of this study was to evaluate
changes in body mass index (BMI) and
food intake among children at schools
that received the HSB intervention. A
full report of the HSB evaluation is
presented elsewhere (20). It was hy-
pothesized that children at the schools
receiving the intervention would show
an increased intake of healthy foods
and beverages, and a modest decrease
in body weight, compared to children in
the control arm.
MATERIALS AND METHODS
Study design and sample
This was a prospective study target-
ing boys and girls 9–11 years of age in
the 5th and 6th grades and their families
during a 6-month school period from
5 May–31 October 2008. The sample was
pooled from six schools that had been
waitlisted and randomized for receiving
the HSB. Four of these six received the
intervention; the remaining two schools
served as controls. This allocation was
assigned by simple randomization. Ex-
perimental and control schools had been
matched according to social condition.
The school districts that participated in
this study comprised neighborhoods of
vulnerable social sectors in which mac-
roeconomic conditions are compatible
with very-low, low, and lower-middle
income standards.
After obtaining parental consent, all
children from the participating grades
were invited to take part in the study;
only those over the age of 11.9 years
(decimal age) and/or any child that
presented a chronic or acute illness that
would impact normal eating behavior
were excluded. A total of six schools
were evaluated at baseline (T1) in May
2008 and at post-intervention (T2) in
October 2008 (Figure 1).
The intervention
For the intervention arm, the par-
ticipating grades took part in four work-
shops: three for the children (Healthy
Eating, Body in Motion, and Healthy
Body); and one for their parents/
caregivers. Workshops lasted 40 min-
utes, were conducted monthly by an
interdisciplinary team, and had an inter-
active modality. Because the children’s
workshops took place during school
hours, attendance was the same it would
be for a normal school day and was not
considered exclusion criteria. Parents’
and/or caregivers’ attendance was 53%
and was not considered exclusion cri-
teria. The intervention consisted of five
parts: the four workshops, plus modifi-
cations to the school cafeteria menu.
Workshop 1: Healthy Eating. The first
workshop aimed to help children identify
healthy foods, understand why healthy
foods improve health, and contemplate
the disadvantages of including competi-
tive options in their diet (e.g., pros and
cons of fat and sodium consumption).
This workshop specifically encouraged
the intake of five healthy food items
targeted by the program: orange juice
(100% orange, no sugar added), whole
fruits, low-sugar cereal, skim milk, and
vegetables (fresh, canned, or cooked).
Workshop 2: Body in Motion. The sec-
ond workshop aimed to get children
motivated about physical activity, and to
understand the health-related benefits of
regular exercise.
Workshop 3: Healthy Body. The third
workshop sought to help children estab-
lish the connection between good eating
habits, regular physical activity, and a

Rev Panam Salud Publica 34(2), 2013 77
Rausch Herscovici et al. • Gender and school-based obesity prevention in Argentina
Original research
healthy body. An additional goal was
to enable children to identify a healthy
menu based on nutritional components.
Workshop 4: Parent/Caregiver. The
fourth workshop aimed to provide di-
etary education to the children’s parents/
caregivers and emphasized the impor-
tance of physical activity.
School Snack Bar. At the start of the
study, the school snack bar options
were modified to include three of the
aforementioned five healthy food items
stimulated by the program (orange juice,
fruit, and low-sugar cereal).
Outcome measures
Body weight. All participating children
were weighed and measured following
international standards at T1 (baseline)
and T2 (post-intervention). Weight was
taken in kilograms (kg) with a digital,
portable beam scale (Seca Onda Model
843; Seca Corporation, Hamburg, Ger-
many); height was taken in meters (m)
with a wall-mounted body-meter (Seca
Stadiometer 208, Seca Corporation, Ham-
burg, Germany). BMI (weight/height2)
was calculated and standard criteria
were used to classify the status of each
boy and girl. The Z-score (normal or
standardized distribution) of weight and
height was used for each age. Refer-
ences used were all based on BMI cut-off
points that were gender- and age-specific
in keeping with the United States Cen-
ters for Disease Control and Prevention
(CDC) growth charts (21). The BMI cut-
off points were 85th and 95th percentiles
for age and gender for overweight and
obesity, respectively.
Weekly Food Frequency Questionnaire
(WFFQ). This instrument was designed
to collect information related to the chil-
dren’s daily diet (22). It was based on a
listing of foods and beverages consistent
with local patterns of intake. Included
were both the healthy items targeted by
the program, as well as others of high ca-
loric density categorized as competitive
or unhealthy (e.g., hamburgers and hot
dogs, salted packed snacks, chocolate
candy bars and sweets, and sodas and
sweetened beverages).
Additionally, categories were set in
order to determine the number of times
those foods or beverage items were in-
gested weekly. Trained dietitians inter-
viewed the children for an average of 40
minutes each. For each item, responses
were on a scale of: never = 0; once per
week = 1; 2 – 4 times per week = 2; and
daily = 3), and later analyzed according
to the expected intake (1 or more daily
for some; and 2 or more times/week for
others). The expected intake standard
derives from the Food Intake Guidelines
for the Argentine Population, which rec-
ommends a daily intake of five fruits
and/or vegetables (23).
Statistical analysis
One-way repeated measures timed
at two levels (baseline and post-
intervention) were conducted with in-
tervention and control groups, and
controlled for gender to determine dif-
ferences over time between the interven-
tion and control groups. Independent
sample t-test evaluated anthropometric
mean values and comparisons between
genders. Independent sample t-test for
proportions evaluated frequency of
overweight, obesity, and under-weight.
The difference in the measures over
time was evaluated comparing both sub-
groups (intervention and control) with a
one-way ANOVA (analysis of variance).
McNemar chi-square test was used for
the analysis of weekly intake of healthy
or competitive foods. The children’s ages
were collapsed for the analysis of the
data. Data were analyzed using IBM
SPSS Statistics software, version 10 (SPSS
Inc., an IBM company, Chicago, Illinois,
United States) with a = 0.05.
RESULTS
Of the 405 students randomized at
baseline, 387 returned the informed con-
sent (216 intervention and 171 controls);
a total of 369 (91%) were reassessed at
T2. There was no difference between the
representations of both groups (inter-
vention and control) at T2 (51% and 49%,
respectively). The resulting number of
cases from each school was determined
by the rate of acceptance of the informed
consent and by the number of children
in each school grade. Of the participat-
FIGURE 1. Flowchart of participants in an evaluation of a school-based obesity prevention inter-
vention in Rosario, Argentina, 2008
Number of children included in the
evaluation of the intervention
(n = 427)
– Excluded (n = 0)
– Not meeting inclusion criteria (n = 4)a
– Declined to participate (n = 18)
– Analyzed (n = 205)
– Excluded from analysis (n = 9)c
AllocationAnalysis
Randomized (n = 405)
Enrollment
– Allocated to intervention (n = 234)
– Received intervention (n = 216)
– Allocated to control (n = 171)
– Lost to follow-upb (n = 11)
– Discontinued intervention (n = 0)
Follow-up
– Analyzed (n = 164)
– Excluded from analysis (n = 0)c
– Lost to follow-upb (n = 7)
– Discontinued intervention (n = 0)
a Children more than 11.9 years of age and/or children with an illness that affects normal eating behavior.
b Children absent from school on test-day.
c Incomplete questionnaire.

78 Rev Panam Salud Publica 34(2), 2013
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Rausch Herscovici et al. • Gender and school-based obesity prevention in Argentina
ing girls, 89% were pre-menarcheal. The
rate of menarcheal girls was 13.8% in the
experimental group and 11.5% among
the controls.
Table 1 describes the demographic
and anthropometric status of the sample
at baseline. Table 2 describes the demo-
graphic and anthropometric status by
study group and by gender at baseline.
Overall, boys were more overweight and
obese than girls (31% vs. 24.3%), and for
the former, a statistically significant dif-
ference was found in their BMI Z scores,
with boys in the control group being
slightly heavier than boys in the inter-
vention group.
BMI changes
Differences in anthropometric mea-
sures at baseline and at post-interven-
tion by study group and by gender can
be seen in Table 3. No statistically sig-
nificant difference was found between
the experimental and control groups.
WFFQ: Healthy food items and
beverages
The five foods promoted by the pro-
gram (orange juice, whole fruits, low-
sugar cereal, skim milk, and vegetables)
were analyzed according to frequency
of intake (Figure 2). Analyses were per-
formed for boys and girls separately,
comparing outcome of the control to
intervention groups at T2. When apply-
ing McNemar’s chi-square test, boys in
the experimental group failed to increase
their intake of the healthy foods targeted
by the program, and they did not differ
from the control group on the remaining
variables. Contrarily, when compared to
their controls, girls in the experimental
group tended to increase their intake of
the five foods targeted by the program;
this attained statistical significance for
skim milk (P = 0.03) and orange juice
(P = 0.05). Girls of the control group
showed a decrease (albeit non-significant)
in their intake of skim milk and of low-
sugar cereals.
WFFQ: Competitive food items and
beverages
Figure 3 shows the changes in the in-
take of competitive foods. Sweets, choco-
late candy bars, salted packed snacks,
and sodas and sweetened beverages
were categorized as 1/day; hotdogs/
hamburgers as more than 2–4 times/
week. Girls in the intervention group
showed an overall trend to decrease
intake of competitive foods; this attained
statistical significance for hamburgers
and hot dogs (P > 0.001). Girls in the
control group presented an irregular
pattern of change regarding intake of
competitive food items, and showed a
significant decrease in their intake of
hamburgers and hotdogs (P = 0.008).
Of the five competitive food items mea-
sured, boys in the intervention group
attained a statistically significant reduc-
tion in the consumption of hamburgers
and hot dogs (P = 0.01); no statistically
significant change was observed for boys
TABLE 1. Baseline demographic and anthropometric data of participants in an evaluation of a
school-based obesity prevention intervention, by group, Rosario, Argentina, 2008
Variable
Intervention group
(n = 216 )
Control group
(n = 171 ) P value
Girls (%) 53 47 0.376a
Age in years (mean ± SD) 9.64 ± (0.77) 9.76 ± (0.68) 0.2a
Weight status, n (%)
Underweight 2.8 3.5 0.946b
Normal weight 73.6 63.2 0.071b
Overweight 15.7 15.2 0.957b
Obese 7.9 18.1 0.341b
Mean BMI ± SD 21.0 ± 5.1 20.7 ± 5.0 0.014a
Mean BMI Z-score ± SD 0.71 ± 1.1 0.65 ± 1.1 0.021a
BMI: body mass index.
a Two sample t-test.
b T-test for proportions.
TABLE 2. Baseline demographic and anthropometric data of participants in an evaluation of a
school-based obesity prevention intervention, by group and gender, Rosario, Argentina, 2008
Variable
Intervention group
(n = 216 )
Control group
(n = 171 )
Boys (n = 105) Girls (n = 115) Boys (n = 91) Girls (n = 80)
Weight status/gender n (%)
Underweight 0 (0.0) 6 (5.2) 3 (3.3) 3 (3.8)
Normal weight 74 (73.3) 85 (73.9) 52 (57.1) 56 (70.0)
Overweight 18 (17.8) 16 (13.9) 14 (15.4) 12 (15.0)
Obese 9 (8.9) 8 (7.0) 22 (24.2) 9 (11.3)
TABLE 3. Differences (Dif) in anthropometric data at baseline (T1) and at post-intervention (T2) of a school based obesity prevention intervention,
by study group and by gender, Rosario, Argentina, 2008
Girls (n = 187) Boys (n = 182)
Measure T1 T2
Dif a
%
Dif b
(95% CI) PcT1 T2
Difa
%
Difb
(95% CI) Pc
BMI
Control group 18.3 18.9 0.56 0.02 0.9 19.5 20.1 0.6 –0.15 0.19
Intervention group 17.8 18.3 0.58 (–0.27; 0.30) 18.3 18.7 0.4 (–0.37; 0.07)
BMI Z score
Control group 0.2 0.4 0.12 0.02 0.69 0.65 0.73 0.09 –0.03 0.53
Intervention group 0.1 0.2 0.10 (–0.12; 0.08) 0.33 0.39 0.06 (–0.11; 0.06)
BMI: body mass index.
a Difference between baseline (T1) and post-intervention (T2).
b Differences between intervention and control groups.
c One-way ANOVA (analysis of variance).

Rev Panam Salud Publica 34(2), 2013 79
Rausch Herscovici et al. • Gender and school-based obesity prevention in Argentina
Original research
in the control group for any of the com-
petitive food items.
DISCUSSION
Previous findings have indicated that
for prevention of overweight, the focus
should be on pre-menarcheal girls, be-
fore their mean body fat mass tends to
increase (24, 25). In this study, girls at the
schools receiving HSB increased their
intake of the healthy foods promoted by
the program, and decreased their intake
of all the competitive foods itemized
on the questionnaire. Moreover, regard-
ing the latter, girls of both the control
and the experimental groups reported a
significant decrease in consumption of
hamburgers and hot dogs. Boys at the
schools where the intervention was car-
ried out decreased intake of one type of
competitive food (hamburgers and hot
dogs). These results, which suggest that
girls are more amenable to accepting
changes in their dietary intake, are prob-
ably related to the characteristic con-
cern with physical appearance and body
weight that affects this gender early on.
Another potential explanation is in line
with a related study (26), which suggests
that programs grounded in social learn-
ing may be more appropriate for girls,
while structural and environmental pro-
grams involving physical activity may
be more effective for boys (26).
The HSB program evaluated in this
study did not tackle physical activity
specifically, but rather focused princi-
pally on social learning aspects derived
from the workshops, in addition to
modifying the food items offered by the
school snack bar.
The reduction in intake of hamburgers
and hotdogs in three of the subgroups is
hard to explain, but is perhaps related to
a political crisis in the country involving
the agricultural sector. This crisis, which
started in March 2008, precipitated a rise
in the consumer price index for meat,
from 157.39 in February to 205.33 in De-
cember of that year (23, 27).
Both groups of boys increased their
intake of sweetened beverages. That this
increase was greater in the control group
points to a favorable outcome for the
intervention. Because a higher consump-
tion of the latter has been associated
with a greater magnitude of weight gain
(7), the importance of affecting this vari-
able is relevant when addressing obe-
sity prevention interventions. Previous
studies have shown that curbing intake
of sweetened beverages is not an easy
task. An earlier, targeted, school-based,
12-month educational program produced
only a modest reduction in the number of
carbonated drinks consumed, albeit as-
sociated with a reduction in the number
of overweight and obese children (28).
Moreover, the importance of an increase
in orange juice intake must be under-
scored by recent findings showing that
moderate consumption of fresh orange
juice should be encouraged as a compo-
nent of a healthy diet, and that it is not as-
sociated with higher weight or BMI (29).
The absence of a significant change in
weight among participants at the post-
intervention is to be expected given the
short duration of the study. Previous
studies show that most school-based
intervention programs increase knowl-
edge about nutrition, but rarely produce
significant changes in either behavior
or short- to intermediate-term health
outcomes (30, 31). Additionally, current
literature has indicated limited success
FIGURE 2. Comparison of percentage of children (n = 369) that showed positive (increase) versus
negative (decrease) change in healthy food intake before and after a obesity prevention interven-
tion, analyzed by group and by gender, Argentina, 2008
Girls
(n = 109 for the intervention group; n = 68 for the control group)
120100806040200
Control
Interventiona
Control
Intervention
Control
Interventiona
Control
Intervention
Control
Intervention
Increase
JuiceCerealsSkim MilkFruitsVegetables
Decrease No change
25.6 19.2 55.2
32.7 18.7 48.6
25.6 32.1 42.3
29.4 24.5 46.1
16.7 27.8 55.5
27.4 17.9 54.7
20.5 17.9 61.6
19.1 19.6 61.3
24.4 17.9 57.7
28.7 21.350
Boys
(n = 96 for the intervention group; n = 86 for the control group)
120100806040200
Control
Intervention
Control
Intervention
Control
Intervention
Control
Intervention
Control
Intervention
JuiceCerealsSkim MilkFruitsVegetables
21.2 22.4 56.4
18.9 17.9 63.2
24 18 58
24.7 26.9 48.4
15 34 51
13.9 35 51.1
20.9 20.9 58.2
23.2 26.3 50.5
29.1 19.8 51.1
22.1 21.1 56.8
a McNemar’s chi-squared test P ≥ 0.01.

80 Rev Panam Salud Publica 34(2), 2013
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Rausch Herscovici et al. • Gender and school-based obesity prevention in Argentina
rates in obesity prevention school-based
programs for boys and children of lower
income levels (32–35).
Overall, this intervention program’s
results are comparable to those of simi-
lar programs of similar duration and
goals. A recent meta-analysis showed
that even though school-based inter-
ventions were effective, longer-running
programs were more successful than
their shorter counterparts (34, 36). A
4-year study that assessed nutritional
knowledge before, and 3 months after an
intervention, showed that school-based
health promotion had sustainable effects
on nutritional knowledge with remission
of overweight being most pronounced
in girls (37). Current results underscore
those previous findings.
Study limitations
The major limitation of this study
was its duration, considering that a
6-month period will likely fail to reflect
anthropometric changes. Another pos-
sible limitation is the well-documented
problem of obtaining accurate food re-
cords from anyone, adult or child. An
extensive study evaluating the validity
of children’s food records concluded
that precise records are difficult to ob-
tain, require intensive training, and of-
ten have low test-retest correlations (38).
Nonetheless, a recent study compar-
ing “self-reported” to “observed” lunch
fruit and vegetable intake among 4th
graders found that condition assign-
ment did not bias recalled intake (39).
In the present study, care was taken to
minimize any potential bias by having
trained dieticians individually interview
each child and help them retrieve infor-
mation with the aid of food pictures.
Furthermore, this study did not calcu-
late daily energy intake in kcals/day.
Although daily energy intake goes be-
yond the aims of the current study, it
is important for future studies given
that almost 30% of the children in this
sample were overweight.
Conclusions
Even though the HSB program suc-
ceeded in increasing the intake of healthy
food items among girls in the interven-
tion group, it failed to significantly re-
duce their intake of competitive foods.
The positive change in the girls’ intake
underscores the gender differences
among children this age, which appears
to impinge upon the response to a social
learning obesity prevention school-based
program. The overweight evidenced by
the children in this study attests to the
importance of addressing obesity pre-
vention strategies among this vulnerable
population. The schools evaluated by the
study belong to a community of lower-
middle and low social class. Despite
increasing obesity rates among mostly
low-income populations, to the authors’
knowledge this is one of the few inter-
vention studies that has focused on this
segment of the population, and one of
the few randomly-controlled evaluations
of obesity prevention programs in Latin
America, and certainly, in Argentina. A
clear suggestion arising from this study
is to consider gender differences when
planning obesity prevention interven-
tions for school-aged children.
Acknowledgements. We are grateful
to the coordinators of the Cantinas Sa-
ludables (Healthy Snack Bars) program,
FIGURE 3. Comparison of percentage of children (n = 369) that showed positive (increase) ver-
sus negative (decrease) change in competitive food intake before and after a obesity prevention
intervention, analyzed by group and by gender, Argentina, 2008
Girls
(n = 109 for the intervention group; n = 68 for the control group)
120100806040200
Control
Intervention
Control
Intervention
Control
Intervention
Control
Intervention
Control
a
Intervention
a
Increase
Sodas &
Sweetened
Beverages
Salted
Packed
Snacks
Chocolate/
Candy Bars
Sweets
Hamburgers/
Hot Dogs
Sodas &
Sweetened
Beverages
Salted
Packed
Snacks
Chocolate/
Candy Bars
Sweets
Hamburgers/
Hot Dogs
Decrease No change
16 25 59
18.2 27.3 54.5
2.8 6.4 90.8
2.8 8.4 88.8
7.8 16.9 75.3
8.7 13.6 77.7
28.6 16.9 54.5
18.9 25.5 55.6
12.8 34.6 52.6
15 38.3 46.7
Boys
(n = 96 for the intervention group; n = 86 for the control group)
120100806040200
Control
Intervention
Control
Intervention
Control
Intervention
Control
Intervention
Control
Intervention
a
19.3 12 68.7
25.5 17 57.5
2.4 9.588.1
4.3 5.490.3
10.6 14.1 75.3
11.6 13.7 74.7
24.7 25.9 49.4
25.5 27.7 46.8
26.7 26.7 46.6
15.8 34.7 49.5
a McNemar’s chi-squared test P ≥ 0.01.

Rev Panam Salud Publica 34(2), 2013 81
Rausch Herscovici et al. • Gender and school-based obesity prevention in Argentina
Original research
Victor Schvartz, María Mercedes Rubén,
and Laura Giorgi; and to their staff mem-
bers: Monica Tron, Jorge Chiaramonti,
Maximiliano Isa, Carina Zanini, Dante
Benedetich, and Gonzalo D’Alleva. Fi-
nally, we express our appreciation to the
participating children and their families,
as well as to the school officials, for mak-
ing this study possible.
Funding. This work was supported
by the International Life Sciences Insti-
tute (ILSI) Research Foundation (Wash-
ington, D.C., USA, and ILSI Argentina,
Buenos Aires, Argentina).
Conflicts of interest. None.
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REFERENCES

82 Rev Panam Salud Publica 34(2), 2013
Original research
Rausch Herscovici et al. • Gender and school-based obesity prevention in Argentina
Objetivo. Evaluar la repercusión de un programa de prevención de la obesidad
en medio escolar, que busca modificar la ingesta de los alumnos de las escuelas de
Rosario, Argentina.
Métodos. Estudio prospectivo en el cual participaron 405 niños de 9 a 11 años de
edad, realizado en seis escuelas de las zonas pobres de Rosario, Argentina, de mayo a
octubre del 2008. Tras emparejamiento en función de la situación socioeconómica, se
escogieron las escuelas mediante una aleatorización sencilla; se evaluaron los partici-
pantes al inicio del estudio (T1) y 6 meses más tarde, después de haber completado
la intervención (T2). El programa consistió en cuatro talleres encaminados a mejorar
los conocimientos de los niños sobre la nutrición y el ejercicio saludables; educar a
los padres y los cuidadores; y ofrecer opciones sanas en la cafetería escolar. Los prin-
cipales criterios de valoración fueron la ingestión de alimentos sanos o malsanos por
parte de los niños (evaluada mediante un cuestionario sobre la frecuencia semanal de
consumo de alimentos) y el índice de masa corporal de los niños.
Resultados. Se evaluaron 387 niños en T1 y de ellos 369 contaron con una nueva
evaluación en T2 (205 del grupo de intervención y 164 del grupo testigo). Las niñas
de las escuelas donde tuvo lugar la intervención aumentaron la ingesta de tres de
los cinco alimentos sanos propuestos por el programa (las frutas, las verduras y los
cereales con bajo contenido de azúcar). Se alcanzó una significación estadística con
la leche desnatada (P = 0,03) y el jugo de naranja puro (P = 0,05). Los niños de los
grupos de intervención y de los grupos de referencia no lograron mejorar su ingesta
de alimentos sanos, pero los que pertenecían al grupo de intervención disminuyeron
significativamente el consumo de hamburguesas y perros calientes (P = 0,001).
Conclusiones. Las niñas estaban más dispuestas a mejorar su alimentación. En
términos generales, con el programa, la probabilidad de aumentar el consumo de
alimentos saludables fue mayor que la probabilidad de disminuir el consumo de ali-
mentos malsanos. Es necesario tener en cuenta las diferencias entre los sexos cuando
se diseñan intervenciones preventivas.
Obesidad; prevención primaria; salud del niño; nutrición del niño; alimentos; Argentina.
resumen
Diferencias entre los sexos
en un programa de prevención
de la obesidad en medio
escolar en la Argentina:
un ensayo aleatorizado
Palabras clave