Child weight status is defined as excessive weight adjusted for height, also referred to as body mass index (BMI = kg/m2). In turn BMI percentiles are adjusted for age and gender, using Centre for Disease Control and Prevention (CDC) Growth Charts. Children are considered overweight if their adjusted BMI is between 85th and 94th percentiles and obese if their BMI is at or above 95th percentile (Barlow & the Expert Committee, 2007).
Obesity adversely affects children both physiologically and psychologically. A systematic review of 11 studies (Reilly & Kelly, 2011) has shown that obesity and overweight in children are strongly associated with a risk of developing diabetes, coronary heart disease, stroke and hypertension. Childhood obesity has also been linked to premature mortality in adulthood (Reilly & Kelly, 2011). An Australian study, conducted by Sanderson et al. (2011), revealed a correlation between overweight/obesity and risk of being diagnosed with a mood disorder in adult life. Sanderson et al (2011) also noted that obese girls are at risk for developing depression.
There are a number of risk factors predisposing a child to obesity. According to the Ecological model of predictors of childhood overweight, a comprehensive review by Davison & Birch (2001), these include a) child risk factors, b) child characteristics c) parenting styles and family characteristics; d) community, demographic and social characteristics. Child risk factors are child behaviour patterns which increase the likelihood of gaining excess weight. First and foremost, it is dietary intake. Fat intake is positively associated with weight. The second risk factor is the level of physical activity. The lower this level is, the higher the weight. The third risk factor is child's sedentary behaviour. Drawing upon previous research, Davison & Birch (2001) noted a persuasive link between sedentary behaviour patterns (such as watching TV or playing computer games) and excess weight. Higher levels of sedentary behaviour were associated with overweight; likewise, lowering the level of sedentary behaviour was related to a decrease in overweight. These risk factors are mediated by child characteristics, which include age, gender and genetic susceptibility to overweight. Thus, genetic susceptibility to overweight may interact with dietary intake, therefore be a factor in weight gain. Age and gender are two other variables which may interact with energy intake and, potentially, have impact on weight. "Children's energy needs differ as a function of their rate of growth and the timing of growth spurts differ for girls and boys," (Davison & Birch, 2001, p 162). In Breda et al. WHO COSI report (2012), prevalence of overweight ranged from 19.3% to 49% in boys and from 18.4% to 42.5% in girls, while the prevalence of obesity in boys was from 6.0% to 26.6% and in girls from 5.1% to 17.3%.
Although they emphasize behavioural patterns of children as being of utmost importance, Davison & Birch (2001, p 168) argue that "all risk factors for the development of childhood overweight have their initial beginnings in the family". Children tend to model their parents' behaviour including patterns of dietary intake and preferences for certain foods. Eating practices of overweight mothers are likely to influence children's eating practices and therefore children's weight status. Parental level of physical activity is positively associated with physical activity level in children.
The final factor related to weight status that Davison & Birch (2001) highlight is community, demographic and societal characteristics such as low socioeconomic status, high number of work hours with little leisure time. Families from lower socioeconomic status are at higher risk of overweight/obesity as they have fewer time and financial resources they can make available for children's sporting activities and varied nutritious diets. School environment is also an important factor in weight status. Nutritional value of school lunches, as well as availability of convenience foods and snacks in schools, is important in the obesity epidemic, since substantial part of a child's diet is eaten at school. Availability of school physical education programmes has been cited as being important (Davison & Birch, 2001). Food advertising during children's viewing times has also been named a contributing factor to obesity (Udell & Mehta, 2008). Udell & Mehta (2008) argue that since the media is important in forming societal perceptions, high volume of unhealthy rich-calorie low-nutrient food advertisements on TV during children's viewing times may skew children's perception of healthy foods.
Child obesity is a complex multi-dimensional issue and the above mentioned factors do not work in isolation to determine the risk of becoming overweight, it's their interaction that determines this risk (Davison & Birch, 2001). Therefore, it should be tackled at all levels. At the level of an individual the core goal is to establish healthy eating habits and physical activity patterns. Green and colleagues (2012) propose some in-family strategies for overweight reduction. Parents are advised to limit the amount of time their children spend watching TV, thus decreasing their sedentary behaviour. Together family can also engage in daily physical activity, - not only will this increase child activity level, but also mitigate sedentary lifestyle of the entire family and promote mutual support within the family. A diet low on fat, sodium, cholesterol and sugar has been identified as reducing obesity and cardiovascular disease (Green et al., 2012). CDC website (http://www.cdc.gov) also recommends parents to serve water instead of sugar drinks and encourage fruits and vegetable consumption. Barlow and the Expert Committee (2007) indicate that limiting visits to fast food restaurant and promoting family meals may be beneficial in lowering obesity prevalence.
In their article, Green et al. (2012) also provide some strategies for school implementation. Firstly, they suggest replacing unhealthy items in vending machines with healthy ones. Secondly, there should be a salad bar in every school, ensuring variety of fruits and vegetables in children's daily intake. Thirdly, it is important that schools stopped promoting certain brand of drink, as school is not a place for advertising. Finally, in order to protect psychological, social and physical well-being of overweight children, it is necessary to provide education on the mistreatment of obese children (Green et al., 2012). In addition to these strategies, according to CDC website (http://www.cdc.gov), schools can limit the sale of sugar drink and make free drinking water easily accessible. Schools can also provide daily physical education to increase children's activity levels.
On a larger societal level, governments should establish safety in all neighbourhoods in order to promote physical activity in children. It is also recommended to motivate supermarkets to sell healthier foods. Based on article by Udell &Mehta (2008), a restriction in junk food advertising during children's TV programmes may also be suggested.
Just as none of obesity risk factors in isolation guarantees developing obesity, none of the solutions on their own can guarantee success. These strategies can provide the desired result of combating childhood obesity and overweight globally only working together. It is necessary to provide education, motivation and resources for obese children to make a fundamental change in their weight status. It is important to be socially inclusive of overweight children in order to promote their mental health. It is essential to create healthy diet and physically active environment for overweight children both at home and at school to improve their health status. It is crucial to focus on prevention measures to stop this quiet epidemic from further spread.
