Being thin used to be linked with poverty while obesity was associated with affluence but now that has turned on its head, according to a University of Aberdeen study.
Nowadays poverty is more associated with obesity, whilst childhood obesity rates are falling among the more affluent communities, according to University analysis of childhood data spanning 35 years.
The study - which examined data for 194,391 children aged between five and six years, born between 1970 and 2006, and attending primary schools in the North-east of Scotland – also shows that less children are underweight.
Height and weight measurements of the children were routinely collected by nurses as part of the school entry process.
Researchers studied these alongside other data such as indicators of socioeconomic status to explore year-on-year trends of childhood thinness as described by the International Obesity Task Force – an international dataset used to define overweight and obesity in pre-school children.
Dr Steve Turner, Senior Clinical Lecturer in Child Health at the University of Aberdeen and Honorary Consultant Paediatrician with NHS Grampian, led the study. He explained the background to the research which appears in the journal Archives of Disease in Childhood: "Childhood obesity has been a major focus for UK public health policy makers and funders since prevalence began to arise in the 1980s. As a result, the problem of underweight children has received reduced attention and resources, despite the comparable adverse health effects. Yet poor nutrition in childhood is associated with poor cognitive development and school achievement, reduced future income and fertility."
Last year the Aberdeen team reported trends in childhood obesity in the same school pupil cohort.
This study set out to tackle the 'general lack of evidence to inform public health policy on prevalence of underweight or thinness in children in the UK'.
"Our studies showed that overall thinness prevalence has fallen from an average of 6% to less than 1% over the 35 year span during which measurements were made. Almost 10% of children born in the 1970s and 1980s were more likely to be thin if they came from a less affluent community, but in this population, any socioeconomic gradient was not apparent in those born in the 1990s and 2000s," said Dr Turner.
"This is in contrast with our earlier obesity paper which showed how obesity prevalence was approximately 2% for all children in the 1970s with a slightly higher proportion among more affluent communities. Current obesity prevalence is 10% and rising in the poorest communities and 4% and falling in the most affluent communities.
"Childhood malnutrition has always been a problem for the poorest communities in our society. This is despite increasing affluence in North East Scotland associated with the oil industry and today's children being an average 3cm taller than their parents were as five year olds. It is not all bad news though, the silver lining is an overall fall in childhood obesity for children measured in the 2000s. We will be watching to see if this overall trend continues and extends into the poorer communities."
Explore further: Obesity more of a problem for boys from poor backgrounds shows study of 36 years' data
More information: "Prevalence and year-on-year trends in childhood thinness in a whole population study." S Smith, L C A Craig, E A Raja, G McNeill, S W Turner. Arch Dis Child 2014;99:1 58-61 Published Online First: 6 November 2013 DOI: 10.1136/archdischild-2013-304423
"Growing up before growing out: secular trends in height, weight and obesity in 5–6-year-old children born between 1970 and 2006." Sarah M Smith, Leone C A Craig, Amalraj E Raja, Geraldine McNeill, Stephen W Turner. Arch Dis Child 2013;98:4 269-273 Published Online First: 14 February 2013 DOI: 10.1136/archdischild-2012-302391