Prevalence and influencing factors of BMI and effect of school based intervention among the Grade 8 Schoolchildren in Jaffna district

A school based descriptive cross-sectional study was conducted among 836 students aged between 13-15 years studying at government schools in Jaffna district from June 2016 to November 2017. Anthropometric measurements obtained using electronic height weight machine with the precision of the instrument for height is ≤±0.1cm, and for weight is ≤±0.1kg, and the Body Mass Index (BMI) for age calculated and compared with WHO (2007) standards. Chi-square analyses performed, and odds ratios calculated in SPSS 21.


Introduction
As a transition period of the child to become adult, adolescence is a decisive period of development.
The changes that happening also affect the amount and type of food intake, which has an impact on lifetime nutritional status. As and Body mass index (BMI) is the recommended simple method for diagnosing wasting, overweight and obesity. It is a measure of general health based on height and weight ratio (1). Globally, the prevalence of overweight and obesity among children and adolescents aged 5-19 has risen dramatically from just 4% in 1975 to just over 18% in 2016. The similar trend observed among the boys and girls (3).
Wasting affects more children and adolescents than obesity. The underweight population had 19.7% greater risk of cardiovascular diseases than did the normal-weight (4).

Surenthirakumaran R 1 , Coonghe P.A.D 1 , Kumaran S 1
Several factors influence the level of health in children, such as social environment, their education, personal health practices, healthy child development, and culture (3). The overweight and obese population had 50 and 96% greater risk of Cardiovascular Diseases respectively than did the normal weight (4). Schools are considered as the easy and primary platform to conduct health and nutrition intervention programs. Unfortunately, school-based programs are struggling to achieve the expected outcomes due to various constraints. The aim of the study is to determine the prevalence of wasting overweight and obesity and the underlying socio-demographic and school-related correlate and effect school-level intervention to manage wasting, overweight and or obesity among Sri Lankan.

Methods
A school based descriptive cross-sectional study was conducted among 871 adolescents aged between 13-15 years studying in Grade 8,9 &

Socio-demographic factors of the study participants
Among the study participants, the gender ratio was almost equal to Males (51.4%) and Females (48.6%). All the children were Tamils, and the majority (91.1%) were Hindus. More than 85% of the children were living with both parents. Nearly  Table 1).   Relationship between level of BMI and the socio-demographic factor   Table 5 illustrates the relationship between BMI distribution and school type, students' performance and school-level interventions to protect the students from getting abnormal BMI. Among the students studying in 1 AB school, a majority (52.8%) were having average weight and bivariate analysis illustrated that syllabus available in Science subjects of G.C.E (A/L) in 1 AB schools protect from experiencing abnormal BMI among students as 0.814 times (Table 4). Abnormal BMI distribution was high among the students who were provided with vitamin C (OR 1.457, 95% CI: 0.929-2.284) and folic acid (OR 1.021, 95% CI: 0.878-1.186), while iron and vitamin A supplementation reduces the chance of getting abnormal BMI (Table 5). However, availability of school health club and counselling facility did not protect the students from getting wasting , overweight or obesity. Regarding the performance of students in school, even though the students with slightly more percentage of abnormal BMI students (48.2%) could take part in extracurricular activities compare to the participation in sports meet (47,2%) and sports team (47.5%). None of the observed difference was not significant at p-value 0.05.

Discussion
In this study 28.6 (n= 239) and 19.3% (n= 161) male and female students were having abnormal BMI: Overweight: >+1SD (equivalent to BMI 25 kg/m2 at 19 years), Obesity: >+2SD (equivalent to BMI 30 kg/m2 at 19 years), wasting: <-2SD, i.e. the prevalence of abnormal BMI is high among male students than females. It might be due to the self-perception of female students' body weight may influence their weight management in a healthy range. However, the finding was not supported by another study carried out among 319 nos. of Colombo school children aged 5-15 years, 10.7 and 13.0% of male and female students were having abnormal BMI (7). However, in another study carried out in 2018 among 14 to 15-year-old schoolchildren in the Colombo education zone shared that prevalence of overweight and obesity among adolescents was revealed as 10.8% (CI 9.3-12.5) and 3.9% (CI 3.1-5.0) respectively, with no gender difference (8). Further, in another study carried out among girls aged between 14 and 19 years studying in a national school of Batticaloa, the prevalence of obesity and overweight were 5.5% and 9.4% (9). Anyhow, obesity was more prevalent in females than males and females are more vulnerable to develop obesity-related adverse health outcomes in future (10).
Living in small house, a large number of family members, low monthly income and maternal employment were significantly associated with undernutrition among school children (11). But in this current study, the living style of the students did not have a statistically significant association with BMI.
Further, Science stream students have the chance to be provided with adequate knowledge regarding healthy body weight maintenance. In this study also, the prevalence of normal BMI was high among the students who were studying in schools having advanced level science stream classes. However, the type of school did not have a statistically significant association with BMI of the students. Facilities available in schools such as counselling and health club may help the students and their parents to diag-nose and treat obesity earlier. But in this study, such facilities were not sufficient to protect the students from becoming obese .
Nutrient deficiencies may contribute to fat deposition, and vitamin A and C are significantly lower in obese persons when compared to healthy individuals. In this current study, More abnormal BMI was recorded among the students who received vitamin C. Further, iron deficiency is a common finding among obese patients (12) and folate levels might be influenced by metabolism alteration, which can occur in obesity (13). But in this study, iron supplementation was effective for protection from abnormal BMI distribution, while folic acid supplementation was not useful to reduce abnormal BMI among students. However, no statistical significant association was found between supplementation of nutrients and obesity status.
Having abnormal BMI is one of the factors that could affect the performance of school-aged students (14). However, in this current study, among the students took part in extracurricular activities and sports meet, the incidence of abnormal BMI was high.
It's agreed with one of the study carried out among students aged 5-15 years studying in Negombo schools where prevalence of obesity identified by body fat content was high and reported that as validity of internationally developed anthropometric cut-offs in South Asian children is unsatisfactory; locally regionally developed anthropometric tools should be used for screening of obesity (15). Further, South Asian countries face a double burden of malnutrition characterized by high prevalence of underweight, overweight, and obesity. Understanding the distribution of this public health problem is important to tailor targeted interventions for communities (16)

Conclusion
Nearly 47.2% of the children in the schools have abnormal BMI. None of the school-based interventions was adequate to change the problem. Hence, relevant stakeholders should take appropriate inter-ventions at the school level to reduce the prevalence of thinness, overweight and or obesity among the school students for their better future.