**2. Prevalence**

#### **2.1 Global prevalence**

Obesity in school children is today an uncomfortable reality. The global prevalence of obesity has doubled between 1990 and 2015. Worryingly, the rate of increase in obesity in children is higher than that in adults in many countries [5]. Globally, about 10% of school children in the 5–17 age groups are obese or overweight [5]. The prevalence varies from 30% in America to less than 2% in sub-Saharan Africa. In just three decades, the number of school-going children and adolescents with obesity has increased by 10-fold, from 11 million to 124 million (2016 estimates). In addition to this, another 216 million children were estimated to be overweight though not obese in 2016 [6]. The International Association for the Study of Obesity (IASO) and International Obesity Task Force (IOTF) reckon that 200 million school children worldwide are either overweight or obese [7]. The problem probably starts early in childhood. A 2010 report estimated that 42 million children under the age of 5 were overweight and of these, 35 million lived in developing countries. While the prevalence of childhood obesity may be plateauing in some developed countries, it is showing a steep rise in developing countries of Asia and Africa. Within Asia, China has the highest number (15 million) followed by India (14 million) [4]. Even within nations, certain subgroups like children of migrants and indigenous populations are at greatest risk of obesity [8].

The NCDRisC study pooled data for 2416 population-based studies. This included data of 31.5 million children and adolescents aged 5–19 years. The mean BMI in 1975 was 17.2 and 16.8 kg/m2 for girls and boys, respectively. It was lowest in South-East Asia and East Africa, and highest in Polynesia, Micronesia and Englishspeaking regions. The age-standardised mean BMI for children and adolescents increased all over the world from 1975 to 2016. The increase was 0.32 kg/m2 per decade for girls and 0.40 kg/m2 per decade for boys. The mean BMI for girls and boys in 2016 was 18.6 and 18.5 kg/m2 , respectively. The age-standardised mean BMI in 2016 was still lowest in South-East Asia and east Africa and highest in Polynesia and Micronesia. It was 16.9 and 17.9 kg/m2 for girls and boys respectively South -East Asia and Africa and 23.1 and 22.4 kg/m2 for girls and boys respectively in Polynesia and Micronesia. The regions with the largest absolute numbers of obese children and adolescents were East Asia, the Middle-east, North Africa, South Asia and English-speaking regions. It is predicted that if post-2000 trends continue, then by 2022, the number of obese children will outstrip those with moderate and severe underweight [3].

Peltzer reported that the prevalence of overweight/obesity in school children aged 13–15 years in seven ASEAN countries (excluding Brunei) was 9.9% [9]. The highest prevalence of overweight/obesity in all eight ASEAN countries was in Brunei Darussalam (36.1%), followed by Malaysia (23.7%). It was lowest in Myanmar (3.4%) and Cambodia (3.7%) [10]. Pengpid and Peltzer also studied the prevalence and factors affecting obesity in children in six Pacific island countries of

**219**

*Obesity in School Children in India*

BMI of >30 kg/m<sup>2</sup>

**2.2 Indian prevalence**

overweight and obesity.

'developmental' pathways [4].

**3.1 Genetic factors**

**3. Factors causing obesity in school children**

Obesity is a result of imbalance between calorie intake and energy output. This may seem a facile explanation, but in reality it is due to a complex interplay of many factors. Biological factors can lead to childhood obesity through 'mismatch' and

Obesity is probably polygenic in inheritance. BMI may be 25–40% inheritable. But, like for hypertension and diabetes, behavioural and environmental factors play a big role. Genetics may just account for less than 5% of all cases of childhood obesity [23]. Maternal undernutrition or malnutrition and placental insufficiency lead to epigenetic changes that put these children at greater risk for developing

and 29.9 kg/m<sup>2</sup>

*DOI: http://dx.doi.org/10.5772/intechopen.89602*

Oceania. Among the 10,424 children in the age group of 13–16 years, the prevalence of overweight and obesity was 24.3 and 6.1%, respectively. The researchers used a

. Therefore, their estimate may not be quite accurate [11].

India is caught in a nutrition paradox where stunting and underweight coexist with overweight and obesity in children. National Family Health Survey-4 (2015–2016) reported the prevalence of stunting, wasting and underweight in children <5 years to be 38%, 21% and 36%, respectively. In this survey, overweight was defined as weight for height being more than 2 SD above the median of the reference population. By this definition, 2% of Indian children under the age of 5 were overweight. Unfortunately, data of older children are not forthcoming from this survey [12]. The prevalence of overweight/obesity among adolescent Indian children rose from 9.8% in 2006 to 11.7% in 2009 [13]. Lobstein and Jackson-Leach computed that there will be 17 million obese children in India by 2025 [14]. This trend is reported from all over India, both in urban and rural areas. Prevalence of overweight/obesity in children in Delhi increased from 16% in 2002 to 24% in 2006 [15]. A study done in the urban areas of Udupi in South India, found prevalence of overweight and obesity in school children to be 10.8 and 6.2%, respectively [16]. Another study from Central India found 3.1% (95% CI 2.5–3.8) of children between 10 and 17 years to be overweight and 1.2% (95% CI 0.8–1.8) to be obese and overall 4.3% were overweight/obese [17]. From Surat, in Western India, Gamit et al. reported the prevalence of overweight and obesity to be 10.2 and 6%, respectively [18]. In Kanpur, the prevalence of overweight and obesity were 4 and 2%, respectively. The authors attributed this low prevalence, when compared to other studies from North India, to local dietary habits [19]. A systematic review conducted by Gupta et al., reported that prevalence of overweight, among 5–19 years children, ranged between 6.1 and 25.2%, while that of obesity ranged between 3.6 and 11.7% [20] Khadilkar et al., in 2010, estimated the combined prevalence of overweight and obesity to be 19.6% as per IOTF classification, while this was 27% according to WHO definitions [21]. Among adolescence, between 10 and 17 years, the percentage was 22.3 (as per IOTF cut off) and 29.8% (as per WHO cut off), and these age groups should be considered most vulnerable for adiposity [22]. The estimates will swing widely till all investigators adopt standard criteria for measurement of

to define obesity and defined overweight as a BMI between 25

Oceania. Among the 10,424 children in the age group of 13–16 years, the prevalence of overweight and obesity was 24.3 and 6.1%, respectively. The researchers used a BMI of >30 kg/m<sup>2</sup> to define obesity and defined overweight as a BMI between 25 and 29.9 kg/m<sup>2</sup> . Therefore, their estimate may not be quite accurate [11].
