**3.1 Genetic factors**

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

overweight and obesity when exposed to energy-dense foods and sedentary lifestyles when compared to children born of mothers with adequate nutrition. Maternal obesity or hyperglycaemia can also cause epigenetic changes, which predispose the children to increased deposition of fat tissue. Recent studies reveal that paternal obesity can also have an adverse effect on the offspring through epigenetic effects [4].

### **3.2 Individual factors**

#### *3.2.1 Gender*

The GDB Collaborators Group did not find any gender difference in prevalence of obesity in children <20 years. In countries with high-medium and high SDIs, the prevalence was higher in boys than in girls with the trend reversing in late adolescence [5]. The NCDRisC study also reported that gender disparity had narrowed considerably all over the world by 2016. They reported a flattening of the curve for both sexes in North-western Europe, high-income English-speaking countries and Asia-Pacific regions. The plateauing was also seen for boys in South-western Europe and girls in Central and Andean Latin America. In contrast, a rise in BMI was noted for both sexes in East and South Asia and for boys in South-east Asia. The prevalence of obesity was highest in Polynesia and Micronesia in both sexes being 25.4% in girls and 22.4% in boys. This was followed by the high-income English-speaking countries. Obesity prevalence was between 1 and 2% in Cambodia, Burkina Faso, Vietnam, Ethiopia, India, Madagascar, Republic of Congo, Japan, Nepal, Niger and Chad. The number of girls with obesity increased from 5 million in 1975 to 50 million in 2016. For boys, the numbers are 6 million and 74 million, respectively [3]. However, other studies do report differences. The prevalence of overweight/obesity in children and adolescents is more in boys than in girls in developed countries (23.8 and 22.6%, respectively). In developing countries, it is lesser in boys than in girls (12.9 and 13.4%, respectively) [24].

Studies from different parts of India also show that it is more common in boys than in girls. Ramachandran et al. reported the prevalence of overweight to be 17% in boys and 15.8% in girls in the age group 13–18 years from Chennai [25]. In the study from Udupi in South India, the prevalence of overweight and obese were 11.0 and 7.1%, respectively, in boys and 10.6 and 5.4%, respectively, in girls [16]. Researchers from Wardha, in Central India, reported the prevalence of overweight/ obesity to be 4.4% in boys and 4.3% in girls [17]. In Pune, in Western India, the prevalence of overweight in children in the age group 9–16 years was 27.5% for boys and 20.9% for girls [26]. In Surat, the prevalence of overweight and obesity in boys was 12.4 and 8.2%, respectively, and in girls it was 7.2 and 2.7%, respectively [18]. Kapil et al. reported the prevalence of obesity in children aged 10–16 years in Delhi to be 8.0% for boys and 6.0% for girls [27]. Chhatwal et al. also found higher prevalence of obesity among boys than girls. They attributed it to the cultural advantages that boys enjoy in India. They get larger helpings of food at home, snack more as they have greater freedom to go out and also participate negligibly in doing household chores. The gender disparity was highest in the most affluent socio-economic groups. Among children going to the affluent school, the prevalence of overweight was 25% in boys and 16.6% in girls (p = 0.001). The prevalence of obesity was 19.9 and 13.3%, respectively (p = 0.003). The prevalence was similar among boys and girls in the lower-income schools. They also found that only at the age of 15 years was prevalence of obesity/overweight more in girls than boys. This is explained by the pubertal hormonal surge and growth spurt that occurs earlier in girls than in boys [28]. These findings are reiterated in the systematic review of 28 studies by

**221**

**Figure 1**.

*Obesity in School Children in India*

1.5–28% respectively [2].

health food options odd [33].

*3.2.3 Dietary factors*

*3.2.2 Age*

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

adolescent boys than girls in India [2].

Ranjani et al. who found that overweight and obesity were slightly more common in

There is a distinct age pattern in childhood obesity. In their longitudinal study on 8544 children, Whitaker et al. reported that the prevalence of obesity was 13% at 9 years and dropped to 9% at 14 years and then increased again [29]. The GDB Collaborators Group also reported that the prevalence of obesity decreased with age till 14 years and then increased [5]. In the American NHANES 1999–2000 survey, the prevalence of overweight/obesity did not vary much in the age groups of 6–11 and 12–19 years (15.3 and 15.5%, respectively) [30]. The findings by Chhatwal et al. in Ludhiana mirrored Whitaker's study. Prevalence of obesity declined from 18.5% at 9 years to 7.6% at 14 year-end then again spiked at 15 years to 12.1% [28]. Ranjani et al. found that prevalence of obesity in under-fives was less than 2% across India. In children >5 years, it varied from 2 to 8%. Overweight rates were about 2× higher and were higher in North and East India than in South India. Among adolescents, the overall prevalence of overweight and obesity ranged between 3 and 24.7% and

With globalisation, the dietary mores of Indian children has also started changing rapidly. Gulati et al. found that a majority of children surveyed in four urban centres preferred to eat out; they felt that home food was 'old-fashioned'. Almost half of them also had their evening meals while watching television [31, 32]. Adolescents associate 'junk food' with independence and convenience and consider

In the Udupi study, there was no statistical correlation between frequent consumption of carbonated drinks and being overweight/obese [16]. But in Oceania, Pengpid and Peltzer found that consumption of >1 carbonated drink per day

A drastic behavioural change is seen in Indian children in senior secondary schools. Those interested in taking competitive examinations stop physical activity totally and adopt a sedentary lifestyle. They enjoy eating packaged food items to relieve stress. These are usually energy-dense high fat, sugar and salt (HFSS) foods. Both nocturnal snacking and consumption of HFSS foods in the breaks between study sessions can lead to significant weight gain. Snacks rich in refined sugars and fats are habit forming and children get addicted to their flavours and tastes. This perspective is supported by a growing body of neuroscience researchers who have demonstrated that the chronic consumption of energy-dense foods brings about changes in the brain's reward pathways that are central to the development and maintenance of habits. While it is difficult to precisely define 'eating behaviour', such habits are associated with pleasure centre in the brain (neural reward circuitries)—characterised by symptoms such as loss of control while eating, over consumption and/or binge eating, continued consumption of high calorie foods despite the knowledge of its negative consequences and inability to cut down despite the desire to do so [34, 35]. The vicious cycle of obesity in school children is shown in

The reinforcing value of food is higher among obese children than among children with normal weight. In general, bland foods are not eaten in excess; whereas, highly palatable foods are often consumed even after an individual's energy requirements have been covered. Some children fall prey to vicious cycle of impulsive

increased OR for obesity by 1.32 (95% CI 1.09–1.61, p < 0.01) [11].

Ranjani et al. who found that overweight and obesity were slightly more common in adolescent boys than girls in India [2].
