Association between socioeconomic status and obesity among 12-year-old Malaysian adolescents
Association between socioeconomic status and obesity among 12-year-old Malaysian adolescents
Aryati Ahmad 0 1
Nurzaime Zulaily 0 1
Mohd Razif Shahril 0 1
Engku Fadzli Hasan Syed Abdullah 1
Amran Ahmed 1
0 Faculty of Health Sciences, Gong Badak Campus, Universiti Sultan Zainal Abidin , Kuala Nerus, Terengganu , Malaysia , 2 Faculty of Informatic & Computing, Besut Campus, Universiti Sultan Zainal Abidin , Besut, Terengganu , Malaysia , 3 Institute of Engineering Mathematics , Pauh Putra Campus, Universiti Malaysia Perlis, Arau, Perlis , Malaysia
1 Editor: Madhavi Bhargava, Yenepoya Medical College, Yenepoya University , INDIA
The epidemic of obesity in developed countries is commonly associated with poor dietary habit and sedentary lifestyle. However, other determinants, including education background and family income, may contribute towards the problem especially in developing countries. This study aimed to determine the influence of socioeconomic status (SES) on obesity among 12-year-old school adolescents in Terengganu, Malaysia. Body weight and height were measured and BMI was categorised based on WHO z-score cut-off points. Information was obtained from self-reported questionnaire on parents' education background, family income and occupation. A total of 3,798 school adolescents aged 12 years (44% boys and 56% girls) were recruited. There was no significant difference in BMI status between boys and girls, or between rural and urban participants. There were significant differences between BMI categories and gender, household income and SES level within rural areas. In the urban areas, significant differences were found between BMI categories and gender, parents' occupational and educational level, household income and size, and SES level. A logistic regression model found several SES factors to be predictors of obesity in this population, namely, gender, household size, father's occupation level, household income level and SES level. Each component of SES has been significantly associated with the BMI category of school adolescents, particularly in the urban areas. This suggests the requirement of multifaceted approaches, including the role of family, society and authorities, in the effort to curtail adolescent obesity.
During the past three decades, the world prevalence of obesity among children and adolescents
has escalated dramatically [
]. In Asia, the epidemic has now become a significant public
gov.my. To obtain the data, please send a request
to the above addresses quoting the following
information: Research title: Childhood Obesity In
Terengganu: Determination Of Prevalence, Risk
Factors and Consequences Using a Health Status
Surveillance, Monitoring And Decision System
(HEMS-System), Grant no.: FRGS/2/2013/SKK/
UNISZA/01/1, Principal Investigator: Dr. Aryati binti
Ahmad, Institution: Universiti Sultan Zainal Abidin
Funding: This study has been funded by the
Malaysian Ministry of Higher Education under
Grant Number FRGS/2/2013/SKK/UNISZA/01/1
(https://www.mohe.gov.my/en/). The funders had
no role in study design, data collection and
analysis, decision to publish, or preparation of the
Competing interests: The authors have declared
that no competing interests exist.
health problem, mainly in the low and middle-income countries. In Malaysia, the national
prevalence of obesity has increased from 5.7% in 2011 to 11.9% in 2015 [
]. Childhood and
adolescence obesity imposes both short and long term negative effects on health and
wellbeing. Children and adolescents who are obese are likely to become obese as adults  and are
at greater risk of developing diabetes mellitus type 2, sleep apnoea, and cardiovascular, bone
and joint diseases, as well as social and psychosocial problems such as stigmatisation and poor
Obesity has been associated with numerous risk factors including genetics, lifestyle and
certain diseases, and medication intake. Lifestyle factors, mainly high-energy intake and reduced
physical activity, have been identified as key factors leading to obesity particularly in
]. Nonetheless, obesogenic environmental factors, including socioeconomic status
(SES), have emerged as also contributing to the obesity problem, although these factors may
need an extensive investigation. Through appropriate and suitable intervention programmes,
obesity can be prevented and treated. A broad understanding of this epidemic and its
associated factors will help to guide the proper development of population-based policies and
effective intervention programmes. Although many studies have revealed the association between
SES and obesity, the impact of these factors on BMI status among adolescents in Malaysia,
specifically in a sub-urban state such as Terengganu, is unclear.
This study aimed to determine the influence of socioeconomic factors on the prevalence of
obesity among Malaysian adolescents in Terengganu, and to provide evidence on the
contribution of environmental factors towards the epidemic of obesity among the adolescents. These
data can be used as a basis to develop and implement relevant intervention programmes.
Study design and sampling
This cross-sectional study was conducted from November, 2014 to June, 2015 and involved all
12-year old school adolescents from all government primary schools in Kuala Terengganu and
Besut districts of Terengganu, a state in the East Coast Region of Peninsular Malaysia. These
two districts were selected based on demographic and logistic factors as approved by the
Malaysian Ministry of Education and Terengganu State Education Department. Nevertheless,
after careful research prior to selection, these two districts covered both urban and rural school
A total of 3,798 school adolescents comprising 1,667 boys (44%) and 2,131 girls (56%)
participated in this study. Participants were also sub-classified based on school locations (urban vs.
rural) set by the Terengganu State Education Department for analysis purposes.
Parental consent for students' participation was obtained prior to the measurements. Data on
height, body weight, age and gender were obtained from the 2015 National Fitness Standard
(SEGAK) assessment test and uploaded into a specific database named the Health Monitoring
and Surveillance System (HEMS) [
]. The SEGAK is a mandatory physical fitness test that is
conducted twice a year in all government schools in Malaysia. Information on parents'
education background, family income and occupation were obtained from self-reported
questionnaires. Verification of self-reported information was cross-checked with the schools' database.
The SES level was determined from these three components [
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Height and weight were measured by trained physical education (PE) teachers in each school
according to the reference material and standardised protocol provided [
]. Body mass and
stature were measured using calibrated analogue health scales to the nearest 0.1 kg and 0.1 cm,
respectively. At the time of data collection, all participants were apparently healthy and all
measurements were taken in light sports attire without shoes during mornings or early
afternoons. Data on height, weight, gender, and age were used to compute the BMI-for-age Z-score
using WHO AnthroPlus software . The BMI was calculated by dividing the body weight in
kilograms (kg) by the height in metres squared (m2). Teachers-measured weight and height
met excellent reliability criterion (i.e. based on ICC values) suggesting that PE teachers'
measurements were reliable. The intra-class coefficient (ICC) for weight, height and BMI were
0.93, 0.98 and 0.91, respectively, which indicates substantial reliability. The BMI categories
were defined using age- and sex- specific cut-off points relative to the WHO 2007
classifications . The interpretation of the cut-offs classifies overweight as having a z-score > +1SD,
obesity as having a z-score > +2SD and thinness as having a z-score < -2SD.
Some SEGAK data were not available from several schools due to inappropriate data entry by
the PE teachers. The total population of 12 years old school adolescents for two districts was
9,624. However, only complete returned questionnaires were considered in the analysis
(n = 3,798). The results were examined for extreme values where reported BMIs were below
-5SD and exceeded +5SD, which were the arbitrary cut-off points stipulated by NHMS [
Descriptive statistics were presented as means with their standard deviation, or percentage of
prevalence to describe the characteristics of the participants' mean weight, height, age and
BMI. Independent sample t-tests were used to test differences in means of BMIs between
genders and school locations (rural vs. urban). Pearson's chi-square test was used to determine the
association between BMI categories and SES levels and their components. Logistic regression
reporting odds ratios (ORs) was used to determine the factors associated with obesity by
comparing the non-obese (BMI z-score <+2SD) and obese groups (BMI z-score >+2SD), based
on WHO 2007 growth reference . Multivariable models were adjusted for gender, school
locations, parents' occupation level, parents' education level, socioeconomic level, household
income and household size. Data were analysed using IBM SPSS Statistics for Windows,
Version 22.0 software (IBM Corporation, Armonk, New York, USA). A two-sided P value of less
than 0.05 was considered as statistically significant.
This study obtained ethical approval from the Universiti Sultan Zainal Abidin Human
Research Ethics Committee (UHREC) (Reference: UniSZA.N/1/628-1Jld.2 (11)). Permission
to conduct the study was obtained from the Malaysian Ministry of Education and Terengganu
State Education Department. Informed written consent from parents to participate in this
study was obtained prior to the measurement. Consent to publish the data was obtained from
the Malaysian Ministry of Education and Terengganu State Education Department.
The anthropometrical characteristics of participants are shown in Table 1. Overall, the mean
BMI of boys was not significantly different to that of the girls: 18.9±4.7 kg/m2 and 18.8±4.3 kg/
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m2, respectively. Similarly, the BMIs of boys and girls of the urban school locations did not
differ from those of their rural counterparts.
Most (60.7%) participants were classified as of normal weight, whereas 9.6%, 15.6% and
14.1% were classified as thin, overweight and obese, respectively (Table 1). The proportions of
boys who were thin and obese were higher than girls, while the girls with normal weight
outnumbered the boys. In contrast, the percentage of overweight boys and girls was similar.
Nonetheless, a significant association was found between BMI categories and gender
throughout all the participants (P<0.001, χ2 = 36.6) (Table 2).
Table 2 shows the association between BMI categories and SES in school locations (rural
and urban). There was a significant association between BMI categories and gender within
rural (P<0.001, χ2 = 34.4) and urban (P<0.001, χ2 = 18.6) school locations. The prevalence of
thin, overweight and obese boys was higher in the rural location compared to the urban.
However, the opposite trend was observed among girls, except for the prevalence of obesity.
Significant associations were also found between BMI categories among urban school adolescents and
mother's occupational level (P = 0.015, χ2 = 20.5), father's occupational level (P<0.001, χ2 =
46.9), mother's educational level (P = 0.011, χ2 = 21.4), father's educational level (P<0.001, χ2 =
34.1), household income level (P<0.001, χ2 = 37.3) and household size (P = 0.039, χ2 = 13.3).
Among the rural school adolescents, no association was found between BMI categories and
these variables, except the household income level (P = 0.011, χ2 = 16.6). The SES level was
determined based on the three components of occupation, education and income level.
Significant associations were found between BMI categories and SES level among both rural and
urban school adolescents (P = 0.044, χ2 = 13.0 and P<0.001, χ2 = 40.6, respectively). In rural
school locations, there was an association between BMI categories and three variables (gender,
household size and SES level), whilst in urban areas a weak association was found with all
variables (Table 3).
Table 4 shows that gender was moderately associated with obesity; boys were 1.6 times
more likely to be obese (adjusted odds ratio (aOR) 1.66; 95% confidence interval (CI) 1.28,
2.05). An equally strong predictor was adolescents with high SES level (aOR 2.26; 95% CI 1.25,
4.06), while adolescents with a medium SES level had a minor increase in their risk of obesity
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aBMI categories versus genders, parental occupation level, parental education level, SES level, household income level, household size within rural area (Pearson's
bBMI categories versus genders, parental occupation level, parental education level, SES level, household income level, household size within urban area (Pearson's
chisquare test) Parental occupation classified based on MASCO 2008 (1st level: Elementary jobs, 2nd: Administrative & operational jobs, 3rd level: Technician job, 4th level:
Professional jobs; SES level classified based on Boey et al. (2003); Household income level (Low: <MYR 2300, Middle: MYR 2300±5599, High: >MYR5600); Household
size (Small: <5 persons, Medium: 5±7 persons, Large: >7 persons)
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(aOR 1.5; 95%CI 0.98, 2.29). The high household income group was similarly associated with
obesity (aOR 1.73; 95% CI 1.04, 2.9). Nonetheless, as household size increased, the adolescents
were less likely to become obese with a 36% lower risk in the medium household size group
(aOR 0.64 95% CI 0.45, 0.91) and 50% less risk in the large household size group (aOR 0.5 95%
CI 0.35, 0.72).
Obesity is a well-known public health problem among the world's population, including
adolescents. Many factors have been associated with the epidemic of obesity; particularly the
imbalance between energy intake and energy expenditure. However, other factors such as SES
may play a substantial role in the rise of obesity in adolescents. To our knowledge, this is the
first study to investigate the association between SES and BMI categories among school
adolescents in Terengganu, Malaysia and to compare the rural and urban school locations.
Surprisingly, the present study showed no difference in the mean BMI between boys and girls, either
as a whole or in rural and urban school locations. This is in contrast with the SEANUTS study,
in which a significant difference in the mean BMI was found between boys and girls [
Similarly, this trend was also found in another study conducted in Selangor [
]. The disparity
between the present findings and the previous studies might be explained by the difference in
the study population. While the SEANUTS study was based on adolescents aged 7 to 12 years
old, and the study in Selangor was among children aged 9 to 10 years, this present study was
only conducted among 12-year old adolescents. In addition, no difference was found in the
mean BMI between urban and rural adolescents. This is also contrary to the findings of
previous national and state level studies [
3, 16, 17
However, regarding prevalence, this study found a significant association between BMI
categories and gender. Consistent with the NHMS 2011 study, the prevalence of obesity was
higher in boys than girls [
]. Zalilah et al. also reported similar trends in obese adolescents
aged 10 to 15 years old , but Turkish adolescents showed no association between gender
and prevalence of overweight and obesity [
]. The gender difference between boys and girls
may be explained by physiological changes and difference in lifestyle at this age . In
general, girls tend to have higher BMI as a result from rapid growth and physical changes
associated with early puberty and sexual maturation. Additionally, they may engage in less physical
activity and sports compared to boys. In spite of that, the prevalence of obesity was more
pronounced among boys in this study. While girls were generally more cautious and restrictive
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Data are Odds ratio (OR); 95% confidence interval (CI)
aBinary logistic regression
b Multiple logistic regression; Dependent variable: adolescents were categorised into two groups (obese and non-obese) using WHO 2007. Parental occupation classified
based on MASCO 2008 (1st level: Elementary jobs, 2nd: Administrative & operational jobs, 3rd level: Technician job, 4th level: Professional jobs; SES level classified based
on Boey et al. (2003); Household income level (Low: <MYR 2300, Middle: MYR 2300±5599, High: >MYR5600); Household size (Small: <5 persons, Medium: 5±7
persons, Large: >7 persons)
7 / 11
about their diet [
], boys on the other hand, may consume larger meals and energy [
study conducted among central and northern Malaysian adolescents found that boys
consumed 10.1% higher energy compared to female adolescents [
]. Similar finding was also
reported in a previous longitudinal study, the Young Heart Project [
], in which boys aged 12
to 15 years had a significantly higher intake of energy compared to their counterparts.
High SES has also been associated with an increased prevalence of obesity among children
in other developing countries [
]. In agreement with the literature, the present study showed
that SES may have an association with the BMI status of adolescents. The prevalence of obesity
was slightly higher among rural adolescents of parents with fourth level occupations, mothers
with tertiary education backgrounds and fathers with secondary education backgrounds,
although these did not achieve statistical significance. In contrast to the rural adolescents,
there were significant associations between BMI categories and each of the SES components
among the urban adolescents. Likewise, the prevalence of obesity was also higher among the
urban adolescents with parents with fourth levels of occupation. Conflicting with the study by
Samani-Radia & McCarthy (2011) [
], the prevalence of obesity in this study was also highest
among the adolescents of mothers with tertiary education and families with a high household
income level and small household size. Nevertheless, consistent with the Turkish study [
the highest prevalence of thinness was found in the groups with lowest household income and
largest household size. As reported previously [
], the prevalence of obesity increased as
household income level increased. This suggests the contribution of family income to
influence the eating behaviour and dietary intake pattern among family members. In addition,
when measuring the SES level based on the three components described above, the highest
prevalence of obesity was reported in high income groups in both urban and rural school
locations, respectively. This finding contradicted that of a study of 12 to 15 years old in North
Gaza which found that boys from both low and high SES had the highest risk of overweight
In the present study, several SES factors were found to be predictors of obesity in
adolescents. A direct link was found with household income, whilst household size showed an
inverse relationship with the BMI status among adolescents which accords with the findings
from previous studies [
]. Higher household income and smaller household size have
been reported to be associated with higher purchasing power and food affordability .
Furthermore, a higher parental education level, in most cases, reflects a higher family SES.
Contrary to the findings in another study of Malaysian adolescents, the higher prevalence of
obesity among higher SES adolescents may be explained by the higher percentage of working
mothers in the present study [
]. Behavioural aspects and upbringing are shaped at home;
having a working mother may affect the risk of obesity [
] because, generally, mothers are
more responsible for the dietary intake and activity of their children than fathers; working
mothers, especially blue collar workers [
], may have less time to spend in taking care of their
children. As a result, they may have less control over their children's food intake, eating habits
and physical activity. Longer working hours of mothers has been shown to be associated with
an increase in the BMI of their children [
]. However, Hofferth and Curtin (2005) suggested
that working mothers' contributions to the household income may also change their children's
lifestyle by providing a greater purchasing ability for healthy and nutritious foods and
participation in structured sports [
This study adds to the evidence on associations between SES and BMI categories,
particularly in Terengganu, Malaysia. Very limited data have been published from this state regarding
adolescence obesity and its associated factors. This study has demonstrated the role of gender,
family factor (father and family size) and the impact of related socioeconomic factors (father's
second occupational level and household income). Family members, especially the parents,
8 / 11
have important equal roles in the provision of meals as well as shaping their children's eating
and physical activity habits [
]. The researchers have confirmed that fathers with better jobs
and salary fail to provide adequate monitoring of food intake among their children [
Increases in the level of career, especially in father, have also increased the demand for
awayfrom-home outside food[
]. This evidence can be used as a basis to develop appropriate
public health policies and intervention programmes to specific target populations in order to
combat obesity. Any intervention efforts to curtail adolescence obesity should directly involve the
parents at the earliest stages of childhood development to ensure healthy practices, at home or
elsewhere. One of the limitations of this study is that, unlike the previous national reports [
], this present study does not provide any evidence on the potential role of ethnicity in obesity
due to the lack of participants from other races, such as Chinese and Indian, in Terengganu.
Nonetheless, it is highly recommended that similar studies be conducted in other states of
Malaysia as well as in other Asian countries to determine any ethnic influences in this
problem. In addition, other risk factors, such as dietary intake and physical activity, should also be
measured and interpreted to determine the major causes of this epidemic among adolescents.
This study highlights the influence of each component of SES, primarily education, family
income and occupational status of the parents, on BMI categories of school adolescents
particularly in urban areas. There is a critical need for multifaceted and community-wide
approaches including the role of family, society and authorities in the effort to prevent and
control adolescent obesity. Parents act as the important forces to change and inform their
children's behaviours. Nonetheless, further prospective studies should be conducted examining
other risk factors to determine the real causes of obesity among adolescents.
The authors express their great gratitude to the Malaysian Ministry of Higher Education for
funding this study (FRGS/2/2013/SKK/UNISZA/01/1), and the Malaysian Ministry of
Education with Terengganu State Education Department for permission to conduct this survey. We
would also like to express our enormous appreciation to the PE teachers, parents and students
for their willingness to participate. Special thanks to members of the Health of Adolescents in
Terengganu (HAT) study and also the enumerators for their valuable contribution to this
Conceptualization: Aryati Ahmad, Amran Ahmed.
Data curation: Aryati Ahmad, Nurzaime Zulaily, Mohd Razif Shahril, Engku Fadzli Hasan
Syed Abdullah, Amran Ahmed.
Formal analysis: Aryati Ahmad, Nurzaime Zulaily, Mohd Razif Shahril, Amran Ahmed.
Funding acquisition: Aryati Ahmad.
Investigation: Aryati Ahmad, Nurzaime Zulaily.
Methodology: Aryati Ahmad, Nurzaime Zulaily, Mohd Razif Shahril, Engku Fadzli Hasan
Resources: Aryati Ahmad, Engku Fadzli Hasan Syed Abdullah.
Software: Engku Fadzli Hasan Syed Abdullah.
9 / 11
Supervision: Amran Ahmed.
Validation: Aryati Ahmad.
Writing ± original draft: Aryati Ahmad, Nurzaime Zulaily.
Writing ± review & editing: Aryati Ahmad, Nurzaime Zulaily, Mohd Razif Shahril, Amran
World Health Organization (WHO). WHO AnthroPlus for Personal Computers Manual Software for
assessing growth of the world's children. 2009. p. 1±45.
World Health Organization (WHO). WHO Child Growth Standards [Internet]. 2007 [cited 2016 Oct 28].
Available from: http://www.who.int/growthref/en/
10 / 11
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