Abstract

Background: The prevalence of undernutrition among children has always been higher for Bangladesh. Although over the last decade, the intensity of undernutrition is decreasing, the problem of over-nutrition and obesity is increasing among the children. Aim: This goal of this study is to determine the prevalence of obesity and overweight among children of selected private English medium schools from Dhaka city through anthropometric assessment as well as to assess the association of various lifestyle factors with the incidence of overweight and obesity. Methods: This school based cross sectional study was conducted in selected four different private English medium schools of Dhaka city among one hundred participants (Fifty male and fifty female participants) aged 6-14 years selected by convenience sampling following recommended ethical guidelines. Anthropometric assessment was done by following WHO guideline along with demographic and behavior related data were collected by a carefully formulated and pretested questionnaire. Results: According the WHO growth reference, the prevalence of the overweight and obesity is 77% and 58% respectively. Among various risk factors, consumption of food outside home and having physical education in school etc., along with parental history of obesity showed significant risk association with overweight and obesity. Conclusion: The prevalence of overweight and obesity is substantially high, which is alarming for a developing country like Bangladesh. Behavioral approaches should be followed to address the factors of overweight and obesity among children.

1. Introduction

Bangladesh has been well known for the severity of malnutrition more specifically undernutrition, but Bangladesh is now suffering from the double burden of malnutrition. The term “Double burden” refers to the coexistence of both under-nutrition and overnutrition in the same population, even sometimes in the same households. The low-and middle-income countries are facing this exceptional phenomenon with rising incidence of non-communicable disease such as obesity, diabetes mellitus, coronary heart diseases, etc., with the simultaneous presence of infectious diseases ¹. There is a worldwide upward trend of obesity among population of all age particularly in school-aged children and the prevalence of obesity in Bangladesh is also on the rise as per the pooled analysis of NCD risk factor collaboration ². According to a report from Institute of Health Metrics and Evaluation, USA, the prevalence of overweight increased from 7% in 1980 to 17% in 2013 among adults in Bangladesh ³.

In thrifty gene hypothesis by Dr. Neel, assumed that human kind is subjected to a continuous cycle of famine and feast during evolution. People having higher stored energy have a better possibility of surviving during famine therefore selection of genes, which are more efficient at storing fat occurs. These “Thrifty” genes store more fat even if there is an absence of famine. Development and urbanization provide the availability of food which leads to obesity and other linked metabolic disorders such as diabetes mellitus ⁴. Rapid urbanization in lower income countries such as Bangladesh, can result in a nutritional transition. This transformation includes consumption of more animal fat, more processed food and beverages as well as more salt and sugary snacks ⁵. LBW babies have a higher risk of developing obesity, coronary heart disease as well as non-insulin dependent diabetes mellitus in later life ⁶. These factors also resemble “The Thrifty phenotype hypothesis”. It is mainly based on poor foetal growth and impaired child development, which is caused by poor environmental conditions as well as maternal malnutrition ⁷. These developmental issues are associated with reduced insulin secretion and insulin resistance ⁸, which are associated with obesity and type 2 diabetes ⁹. According to the National Low Birth Weight Survey of Bangladesh, 2003-04, over 35% of babies had low birth weight in Bangladesh ¹⁰. However, the prevalence of overweight and obesity among the children is increasing day by day. It can be hypothesized the prevalence is higher among the students of English medium schools since most them come from higher socioeconomic class ¹¹. There has not been any recent study found on this vulnerable group on obesity and its’ determinants. This study aims to determine the prevalence of obesity and overweight among children of selected private English medium schools from Dhaka city through anthropometric assessment as well as to assess the association of various environmental determinants such as physical activity, dietary behaviour, etc.

2. Materials and Methods

This school based cross sectional study was conducted in randomly selected four different private English medium schools of Dhaka city. School going children aged 6-14 years were selected for this study.

Sample size was calculated using the following formula ¹²:

Here, = Standard normal variate (at 5% type 1 error (P<0.05) is 1.96,

p= Expected proportion in population based on previous study on 1768 children (980 boys; 788 girls) from eight purposively selected schools in different areas of Dhaka city which is 0.05 (5.0%) ¹³,

d= Absolute error or precision, which is set to 0.05.

According to formula, this proposed study should have at least 77 subjects. Therefore, 100 study subjects were included for this study. The sample population was selected by convenience sampling method from different schools in Dhaka city.

Anthropometric data such as height, weight as well as MUAC of the study subjects were measured with precision by standard techniques recommended by WHO. Following indices: BMI-for-age Z score and Height-for-age Z score were calculated in accordance with the WHO growth reference for school-aged children and adolescents ¹⁴. Demographic and behaviour related data were collected by questionnaire.

Study was conducted in accordance with the declaration of Helsinki and ethical clearance was taken from the institutional Ethical Committee. Informed consent from the all participants as well as from the institutional heads were taken and confidentiality of all the participants was ensured.

Data analysis was carried out using statistical software IBM SPSS Statistics 23.0. Anthropometric indices such as BMI-for-age Z score, Height-for-age Z score, were computed from the anthropometric measurements and these were compared with WHO growth standards by using WHO AnthroPlus 1.0.4 software ¹⁵. All data from assessments was tested separately for a normal distribution by Shapiro-Wilk test. If the data were normally distributed, then homoscedasticity will be checked by the Fligner-Kileen test. Chi-square test was done for categorical variables such as anthropometric indices such as Nutritional status, physical activity data etc. Otherwise, if the data were not normally distributed, non-parametric Wilcoxon test was carried out. If data were normally distributed but do not have equal variance then the Welch t-test was done for comparison. In order measure the association, odds ratio was calculated using binary logistic regression.

3. Results

Following Table 1 shows the demographic characteristics of the study population.

The distribution of BMI for age is negatively skewed and most of the data is in between +2SD to +3SD compared with the WHO reference data. The prevalence of overweight is 77% and obesity is 58% irrespective of sex (Figure 1). Among female children the prevalence of overweight is 72% and obesity is 52% compared to 82%, 64% for male children respectively (Table 2).

On the other hand, if we compare the height for age z score with WHO reference data, the distribution is positively skewed. Most of the values are in between -1SD to -2SD from reference mean (Figure 2). According to WHO reference data, 11.3% of children were 3SD below the reference and 28.3% of children are 2SD below than the reference median.

Following Table 3 shows the result for the frequency and association between different risk factors and overweight. It has been evident from the result that frequent consumption of street food, sleeping during the day, outside home eating, having physical education class in school and parental history of obesity shows significant risk association with being overweight.

4. Discussion

Our study shows the cooccurrence of both under nutrition and over nutrition in same population even in same child. Almost 30% of the children are less than 2SD below reference median. Length/Height-for-age reflects cumulative linear growth. Low height for age refers to past or chronic nutritional deficiency and/or chronic or frequent illness. Low length/height-for-age compared to a child of the same sex and age in the reference population can be defined as "shortness". Shortness can be interpreted as pathological at extremely low length/height-for-age, which is defined as "stunting". Length/Height-for-age is generally used as a population indicator rather than for individual growth monitoring ¹⁶. On the other hand, Body mass index (BMI) is a relative measurement of height and weight. BMI reflects body storage of fat and protein ¹⁷. BMI for age Z score is the comparison of BMI with reference data of WHO. 77% of the students are 2SD above than the reference data and among them 58% students are 3SD above the reference median, who are classified as overweight and obese respectively. The prevalence of overweight and obesity is substantially high among the students of English medium schools since most of them comes from well off families. It is really alarming for a developing country like Bangladesh which has no particular policy to prevent childhood obesity in Bangladesh. We have found significant association between several risk factors of obesity. For example, sleeping during the day also act as a factor in the occurrence of obesity. Sleeping during the day reduces the physical activity of the child therefore they do not indulge in required physical exercise ¹⁸. Dietary behaviour is an important factor of obesity. From our study, Obese or overweight children tend to eat outside home and the consumption of fast food and street food is high among the obese and overweight children. Street foods and fast foods are mostly unhygienic ¹⁹ as well as contain high amount of salt, sugar and fat, which can contribute to high energy intake ²⁰. These factors showed highly significant association with the incidence of over nutrition among the study population. Sedentary behaviours such as watching television while eating as well as playing games in mobile phone or computer are determining factors of obesity. Obesity is mainly a polygenic disorder and it can be transmitted to children from their parents. Our study confirms that there is a higher probability of obesity if the child has a family history of obesity as well as children who are exposed to passive smoking tends have higher risk of being overweight. Anthropometric assessments are non-invasive and require less logistics and time than most of the other nutritional assessments ¹⁷. However, anthropometric measurements are prone to measurement errors. Anthropometric measurements below cut-off points cannot indicate the depletion of nutrients since anthropometric indications are the late symptoms of any nutritional deficiency. As a result, subclinical deficiencies can remain undetected. Weight represents both lean mass and fat mass so people having higher lean mass, can be misinterpreted as overweight depending on BMI classification ²¹.

5. Conclusion

Based on our study, the prevalence of overweight and obesity as well as stunting is alarming. It is high to take steps to resolve this issue of over nutrition in order to fulfil sustainable development goal in time. Therefore, we need to develop policies following behavioural approaches to motivate the children to change their negative health behaviours.

Acknowledgements

We would like to acknowledge the Ministry of Science and Technology, Government of People’s Republic of Bangladesh for funding this research as well as the students of the College of Home Economics, Dhaka for helping with data collection.

Statement of Competing Interests

Authors have declared no conflict of interest.

References