Prevalence and predictors of overweight and obesity among adolescents

INTRODUCTION

According to the World Health Organization (WHO), obesity is one of the most common, yet among the most neglected, public health problems in both developed and developing countries.It is estimated that around 41 million children under the age of five years were overweight or obese in 2016. Even though obesity was considered as the problem in high income country, now its prevalence is rising in the middle and low income countries. The number of overweight children under the age of 5 years has increased by nearly 50 percentage since 2000 in Africa. In Asia around half of the children under the age of 5 years were overweight or obese.^1,2

However, the magnitude of the problem among children and adolescents in India is unclear due to paucity of well-conducted nationwide studies and lack of uniformity in the cut-points used to define childhood overweight and obesity.³ A systematic review including Prevalence data from 52 studies conducted in 16 of the 28 States in India concluded that the combined prevalence of childhood and adolescent obesity is higher in north, compared to south India. A combined prevalence of 19.3 percent of childhood overweight and obesity in 2010 showed a significant increase from the earlier prevalence of 16.3 percent reported in 2001-2005.³ A study conducted to examine the prevalence of obesity and overweight in urban school children in Kochi, Kerala, South India identified a prevalence of obesity as 3.0% for boys and 5.3% for girls. The prevalence of obesity (7.5%) and overweight (21.9%) were highest among high income group and lowest (1.5% and 2.5%) among low income group.⁴

Childhood and adolescents obesity occurs as a result of various interrelated factors like hypothalamic, hereditary, metabolic, social, cultural and psychological factors. Sociocultural factors play a vital role in the development of obesity in children and adolescents. Childhood obesity has enduring and far reaching psychological as well as physical impact among children. These problems can last well into adulthood and hence need to be identified and managed at the earliest.

Hence the present study aims to determine the prevalence and predictors of overweight or obesity among adolescents of selected schools of Ernakulam District, Kerala, following revised IAP growth charts for height, weight and body mass index for 5-to 18-year-old Indian children.

METHODS

Study design and procedure

The study was conducted among adolescents with age between 12 to 18 years, studying in eight selected schools of Ernakulam district. The research design adopted for the study was descriptive survey design. Two educational districts were selected randomly and four schools were selected randomly from each district. Permission was also obtained from concerned school authorities and 1340 students studying in grades 7 to 12 were included in the study. The sample size was estimated using the formula for estimation of proportion with relative precision.⁴

Administrative permission was obtained from the Director of General education, District Educational Officer and the principals of selected schools. Approval was also obtained from scientific review committee and institutional ethics committee. After providing adequate information regarding the study, assent was taken from the subjects and consent was taken from their parents.

Measures

Adolescents of age between 12 to 18 years, studying in the selected schools, who were willing to participate in the study were enrolled in the study and data were collected from them using Calibrated weight scale, standing stadiometer and a structured socio -personal performa. Adolescents were classified into overweight and obese based on calculated BMI following revised IAP growth charts for height, weight and body mass index for 5to 18yearold Indian children.^5,6

Calibrated weight scale and standing stadiometer

The weight and height of the subjects were assessed using calibrated weight scale and standing stadiometer respectively. BMI was calculated based on the obtained height and weight.

Socio personal performa

It included 22 items such as age, gender, religion, type of family, area of residence, education of father, education of mother, occupation of mother, occupation of father, number of meals per day, number of snacks per day, frequency of consumption of fast foods, frequency of consumption of junk foods, regularity of exercise, weight teasing by family and friends, presence of disorders related to thyroid and menstruation and family history of obesity.

Data analysis

Data were analyzed using R software using appropriate descriptive and inferential statistics. Socio personal variables and prevalence of adolescent obesity were reported using frequency and percentage. Binary logistic regression was computed to identify the predictors of adolescent obesity. Initially, simple logistic regression was performed to identify the associated factors. The identified factors were then verified using multiple logistic regression models to identify the predictors.

RESULTS

Description of socio-personal variables

Among the subjects, majority (57.61%) of the subjects were females and 52.24% belonged to Hindu religious background. Most of them (70.07%) belonged to nuclear family and 90.9% were residing in urban areas. Majority (82.54%) of the subjects had no family history of obesity and 59.70% of them had no regular exercise. 50.90% of the subjects used to consume 4 meals per day and 40.97% of them consumed fast foods rarely. 36.94% of the subjects used to consume junk foods at least once in a week and 56.49% consumed at least one snack between meals. Eighteen subjects (1.34%) had thyroid disorder. Weight teasing by family members and friends were reported by 59 and 108 subjects respectively.

Prevalence of overweight and obesity among adolescents

Out of 1340 samples, 149 (11.12%) had overweight and 80 (5.97%) had obesity (Figure 1). Among 772 females, 120 (15.54%) were overweight and 38 (4.92%) were obese. Among 568 males, 29 (5.1%) were overweight and 42 (7.39%) were obese. 

Predictors of overweight or obesity among adolescents

Simple logistic regression was performed to identify the predictors of overweight and obesity among adolescents. The predictors identified include: exercise (OR: 0.66, CI: 0.49, 0.86), family history of obesity (OR: 2.35, CI: 0.31, 0.59), consumption of junk foods (OR: 1.17, CI: 1.03, 1.33) and presence of thyroid disorder (OR: 2.71, CI: 0.16, 0.86). The predictors identified were included in multiple logistic regression models with obesity and overweight as dependent variable and all others as independent variables. Multiple logistic regression identified exercise (OR: 0.69, CI: 0.52, 0.93), family history of obesity (OR: 2.24, CI: 0.32, 0.62) and consumption of junk foods as predictors of overweight and obesity among adolescents.

The model specifications (odds ratio and confidence interval of each independent variable) are given below (Table 1).

DISCUSSION

The present study identified that 11.12% of the subjects had overweight and 5.97% had obesity. The prevalence of overweight is more among girls (15.65%) compared to boys (5.06%); whereas, prevalence of obesity is more among boys (7.33%) compared to girls (4.95%).Another study conducted at selected urban schools in Kochi also identified similar prevalence rate. According to the study, the prevalence of overweight and obesity were 21.9% and 7.5% respectively. The study also has a contradictory finding in terms of gender wise prevalence where there is more prevalence of obesity (5.3%)among girls compared to boys (3%).4Similar study conducted at Vadodara showed a higher prevalence of obesity and overweight with 17.6% and 20.2% respectively.⁷

The factors associated with overweight or obesity among adolescents identified in the present study include exercise and family history of obesity. A study conducted at Vadodara identified that annual income of family, frequency of physical training sessions conducted in schools, frequency of restaurant and school canteen food are significantly associated with obesity. Family history of obesity, which is identified as a predictor of adolescent obesity in the present study is identified to have no association with adolescent obesity in the former study.7 Another study conducted at Ghana also identified that children who reported lower participation (<3 times/week) in sports activity were 44% more likely to be overweight or obese.⁸

CONCLUSION

As the prevalence of overweight and obesity has an increasing trend, measures for early identification and prevention of obesity and overweight should be adopted considering its enduring physical and psychological ill effects.