The new study investigates why poorer children are more likely than their better-off counterparts to be obese.
According to the study authors, who are led by Prof. Yvonne Kelly from University College London in the UK, obesity is linked to the development of many chronic diseases that pose significant health and economic burdens.
They explain that children who become overweight and obese are at higher risk of obesity throughout their lives.
Furthermore, overweight and obese children face higher risks of negative economic and social outcomes - in both childhood and adulthood.
As such, investigating the causes underlying childhood obesity is an important area of study from a psychological, economic and public health perspective.
The researchers note that there "is limited evidence on which risk factors attenuate income inequalities in child overweight and obesity," so they wanted to investigate "why these inequalities widen as children age."
To conduct their study, the team used data from the Millennium Cohort Study (MCS), which tracks nearly 20,000 families in the UK.
'Structural causes of socioeconomic inequalities need to be addressed'
Children who were tracked as part of the study were measured at age 5 and again at age 11.
Additionally, the researchers looked into many aspects of a child's environment and health behaviors, such as whether the mother smoked during pregnancy, how long she breastfed the child and whether solid foods were introduced before the age of 4 months.
Fast facts about childhood obesity
- In the US in the past 30 years, childhood obesity has more than doubled in children and quadrupled in adolescents
- Obese youths are more likely to have risk factors for cardiovascular disease
- They are also more likely to have prediabetes.
The team also investigated whether the mother was overweight or obese.
Results showed a strong link between poverty and childhood obesity; at 5 years of age, poor children were nearly twice as likely to be obese, compared with their peers from better socioeconomic backgrounds.
In detail, 6.6% of children from the poorest fifth of families in the sample were obese, while only 3.5% of those from the richest fifth were obese.
Additionally, the team found that by age 11, the gap increased, with 7.9% from the poorest fifth being obese and only 2.9% from the richest fifth.
The researchers went into further detail when they looked into the impact of physical behavior by comparing frequency of sport or exercise, active play with a parent, TV-watching or computer hours, bike journeys and child's bedtime.
They also looked at dietary habits, including whether the child skipped breakfast, and fruit and sweet drink consumption. Doing sport more than three times per week, having an early bedtime and regular fruit consumption were positively associated with downward trends in weight categories.
Maternal smoking during pregnancy and a mother's body mass index (BMI), however, were negatively associated with downward trends across weight categories.
Commenting on their findings, Prof. Kelly says:
"The 'structural' causes of socioeconomic inequalities have to be addressed along with tackling 'inherited' obesity via lifestyle factors that tend to go with lower incomes. Early intervention with parents clearly has huge potential. And evidence from our work suggests that this should start before birth or even conception."
She and her team note that the markers of "unhealthy" lifestyle identified in the study could equate to as much as a 20% additional risk of childhood obesity.
Although the study benefits from a large nationally representative sample, the researchers admit to certain limitations. Firstly, their models were not able to fully explain income inequalities in children's obesity, which suggests that some other risk factors should be considered in future work.
Secondly, the researchers are not able to conclude that there is a causal link between risk factors and income inequalities in overweight and obesity.
And finally, although maternal BMI was included in the "dietary environment" category, it could also reflect genetic as well as shared environment.
Still, the researchers say that more research should be undertaken in this area, given that the underlying processes involved in childhood overweight and obesity involve social, environmental and biological factors. They add:
"A few studies also reveal that socioeconomic inequalities in overweight/obesity widen across childhood. These inequalities are likely explained by differential access to resources and/or knowledge by poorer parents who may practice worse health behaviors."
In March of this year, Medical News Today reported on a study that suggested many parents may not recognize child obesity in their kids.