Girls at greater risk than boys of being overweight at age 7

7 December 2010

Girls are much more likely than boys to be overweight at age 7, a UK-wide study has found.

Researchers at the Institute of Education, University of London, who have been monitoring the weights of more than 11,000 children born between 2000 and 2002, have calculated that girls are almost 50 per cent more likely than boys to be too heavy at age 7. About one in four girls (23%) was overweight at this age, compared with just over one in six boys (18%).

The researchers also found that seven-year-olds with no brothers or sisters are about 25 per cent more likely to be overweight than youngsters with one sibling and about 30 per cent more likely to be overweight than those with two siblings.

The study’s principal author, Dr Alice Sullivan, said: “Girls and only children are also more likely to become overweight between the ages of 5 and 7. It is not clear whether the increased risk for girls is due to them being overfed compared to boys, or because they are involved in less physical activity – perhaps due to the over-protectiveness of parents – or some combination of the two.

“Similarly we do not know whether only children are less active due to lack of siblings, or overfed by indulgent parents. Either way, making parents aware of the increased risk to girls and only children may help to modify their behaviour.”

Dr Sullivan and her colleagues also emphasise that overweight five-year-olds are 25 times more likely than children of normal weight to still be too heavy at age 7. “The fact that children overweight at 5 have an overwhelmingly greater risk of being overweight two years later suggests that ‘puppy fat’ should not be ignored and early intervention is crucial,” they say.

The researchers, who analysed the weights of children taking part in the Millennium Cohort Study, also found that those with an overweight or obese mother, an obese father, and a mother who is a smoker, are at substantially greater risk of being overweight. “This implies that overweight is a family problem,” Dr Sullivan added. “Health messages need to be targeted at mothers in particular.”

The research confirmed that there is a clear link between poverty and overweight. Almost one in four (24%) seven-year-olds in England, Scotland and
Wales whose families were living below the study’s poverty line at both the age 9 months and age 3 surveys was overweight. By contrast, less than one in five (19%) children in families who were not in poverty at either survey was overweight.

The association between poverty and overweight was even stronger in Northern Ireland. Almost one in three (32%) seven-year-olds classified as poor at both surveys was overweight, compared with one in five (20%) of those above the poverty line at age 5 and 7.

A higher proportion of seven-year-olds in Northern Ireland (23.8%) and Wales (22.7%) was overweight than in England (19.9%) and Scotland (19.3%).

The consequences at age 7 of early childhood disadvantage in Northern Ireland and Great Britain (pdf). A report to the Northern Ireland Office of the First Minister and Deputy First Minister, by Alice Sullivan, Heather Joshi, Sosthenes Ketende,
and Polina Obolenskaya will it be available from the Centre for Longitudinal Studies website ( from 9am on Tuesday, December 7.

Further information from:

David Budge:, (off) 020 7911 5349, (mob) 07811 415362

Notes for editors

  1. The Millennium Cohort Study has been tracking children in England, Scotland, Wales and Northern Ireland through their early childhood and plans to follow them into adulthood. It covers such diverse topics as parenting; childcare; school choice; child behaviour and cognitive development; child and parental health; parents’ employment and education; income; housing; and neighbourhood. It is the first of the nationwide cohort studies to over-sample areas with high densities of ethnic minorities and large numbers of disadvantaged families. Surveys of the cohort were also carried out when the children were aged nine months and three years. The study is housed at the Centre for Longitudinal Studies at the Institute of Education. It was commissioned by the Economic and Social Research Council, whose funding has been supplemented by a consortium of government departments.
  2. At age seven, as at ages 3 and 5, height and weight measurements were taken and a measure of Body Mass Index (BMI) derived. Standard cut-offs for overweight and obesity were applied.
  3. The new report builds on a previous report which examined outcomes at age 5:
  4. In the Millennium Cohort Study, families considered to be in poverty are estimated to be living on less than 60 per cent of the average national household income. The poverty line calculation takes into account the number of people in a household.
  5. Data from the fieldwork for the age 7 survey of the Millennium cohort are now available from the UK Data Archive The contract for data collection in MCS is awarded under competitive tender to specialist agencies. For three of the four surveys undertaken to date the data collection was carried out by the National Centre for Social Research.  The agency responsible for the second round of data collection was Gfk-NOP.
  6. The Economic and Social Research Council (ESRC) is the UK’s largest organisation for funding research on economic and social issues. It supports independent, high quality research which has an impact on business, the public sector and the third sector. The ESRC’s planned total expenditure in 2009/10 is £204 million. At any one time the ESRC supports more than 4,000 researchers and postgraduate students in academic institutions and independent research institutes.
  7. The Institute of Education is a college of the University of London that specialises in education and related areas of social science and professional practice. In the most recent Research Assessment Exercise two-thirds of the publications that the IOE submitted were judged to be internationally significant and over a third were judged to be “world leading”. The Institute was recognised by Ofsted in 2010 for its “high quality” initial teacher training programmes that inspire its students “to want to be outstanding teachers”. The IOE is a member of the 1994 group, which brings together 19 internationally renowned, research-intensive universities.

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