Around one in 10 children in England will be obese by 2015, on the basis of recent trends, suggests research published ahead of print in the Journal of Epidemiology and Community Health.
The gap between the most and least affluent sectors of society is also set to widen, with greater numbers of children from less affluent and educated households caught in the obesity trap, the figures indicate.
The authors assessed trends in obesity among children in England aged 2 to 10 and young people aged 11 to 18 for the years 1995 to 2007. The data were obtained from the annual Health Survey for England, which draws on a nationally representative sample of households.
Based on these figures, they then calculated the likely prevalence of obesity in 2015 for these age groups according to social class (manual or non-manual), as determined by the job title of the head of the household.
They used two methods of calculation: linear trends whereby trends remain constant over time; and exponential or power trends, which allow for a speeding up or slowing down of trends over the same period.
Between 1995 and 2007 the prevalence of obesity among boys aged 2 to 10 more than doubled from 3.1% to 6.9%. Among girls in this age group, it rose from 5.2% to 7.4%.
The upward trend stabilised or even fell slightly between 2004/5 and 2007. But the annual prevalence was consistently higher among boys (0.6%) and girls (1.5%) from manual class households.
Among 11 to 18 year olds, obesity prevalence rose from 2.7% to 4.8% among boys, and from 4.7% to 6.1% among girls.
Once again, the annual prevalence was higher (1.2% among boys and 2.1% among girls) for those coming from manual class households, although there is some evidence to suggest a levelling off in more recent years.
Linear trends for obesity prevalence among all boys aged 2 to 10 in 2015 work out at 10.1%; while exponential trends indicate a prevalence of 13.5%. Among girls the equivalent figures are 8.9% and 9.3%, respectively.
But the prevalence for all children from manual class households will be considerably higher than that of children from non-manual households, regardless of forecasting method, say the authors.
In 2015 the prevalence of obesity among boys and girls from manual households will be 10.7% for boys and 11.2% for girls. This compares with 7.9% for boys and 5.4% for girls from non-manual households.
For the older age group, linear projections for young men in 2015 are 8% or 9.5% in the exponential projections. For young women, the equivalent figures are 9.7% and 10.6%, respectively.
The linear trend figures show that one in 10 boys and just over one in 10 girls (10.4%) from manual class households will be obese by 2015. This compares with 6.7% for boys and 8.3% of girls from non-manual households.
Power trends analysis shows similar gaps between the social classes.
"If trends continue as they have been between 1995 and 2007 in 2015 the number and prevalence of obese young people is projected to increase dramatically, and these increases will affect lower social classes to a larger extent," conclude the authors.