Child obesity risk increases almost three-fold in five generations

Children born since 1990 are up to three times more likely than older generations to be overweight or obese by age 10, according to a new study.

Researchers from CLOSER, a consortium of leading UK longitudinal studies, looked at the body mass index (BMI) of more than 56,000 people born in the UK from 1946 to 2001. They found that around one in ten children born in 1946 were overweight or obese by age 11, compared to roughly one in four 11-year-olds today. Younger generations are also putting on weight more rapidly.

These findings will concern policymakers and health care professionals, as it is estimated that the obesity ‘epidemic’ will cost the UK’s National Health Service £22.9 billion per year by 2050.

Since 1946, every generation has been heavier than the previous one – and worryingly, it is the most overweight people who are becoming even heavier. For example, the heaviest 2 per cent of people born in 1946 had a BMI of around 20 by the age of 11, compared to 27 for the most obese children born at the turn of the century.

People are also becoming overweight or obese at an increasingly younger age, say the researchers who have published their findings in the American journal, PLOS medicine. Half the men of the 1946 generation were overweight by the time they were 41 years old, compared to age 30 for men born in 1970. Half the women born in 1946 were overweight by age 48, compared to 41 for the 1970 generation.

While childhood obesity is more prevalent among more recent generations, the majority of today’s children are still a normal weight.

No other study has been able to track weight gain across as many generations, or through as much of their lives (from age 2 to 64 for the oldest participants in this study).

Professor Rebecca Hardy of University College London, one of the report’s authors, explained: “The more of their lives people spend overweight or obese, the greater their risk of developing chronic health conditions such as coronary heart disease, type 2 diabetes, high blood pressure and arthritis.

“While other research has shown that losing weight at any point in adulthood can help reduce the risk, this study indicates that the UK needs to target its public health interventions at younger and younger ages in order to stem the spread of the obesity epidemic.”

This research uses data collected by five British birth cohort studies: the MRC National Survey of Health and Development (also known as the 1946 British birth cohort), the National Child Development Study (also known as the 1958 British birth cohort), the 1970 British Cohort Study, the Avon Longitudinal Study of Parents and Children (also known as Children of the 90s), and the Millennium Cohort Study.

Read the full paper

How has the age-related process of overweight or obesity development changed over time? Coordinated analyses of individual participant data from five United Kingdom birth cohorts, by William Johnson, MRC Human Nutrition Research at Cambridge; Leah Li, UCL Institute of Child Health; and Rebecca Hardy and Diana Kuh, MRC Unit for Lifelong Health and Ageing at UCL, will be published in latest issue in PLOS Medicine.

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Notes to editors

1. BMI is calculated by dividing an individual’s weight in kilogrammes by their height in metres squared. The authors used the International Obesity Task Force guidelines to determine whether a person was underweight, normal weight, overweight or obese.
2. The study only included people of white ethnicity as there were not sufficient numbers of people of non-white ethnicities in the older cohort studies to carry out the analysis on other ethnic groups. The difference between a healthy and an unhealthy BMI differs between ethnicities, so the findings from this study may not be the same for other ethnic groups.
3. The authors used data from five UK birth cohort studies: the MRC National Survey of Health and Development (1946 birth cohort study), the 1958 National Child Development Study, the 1970 British Cohort Study, the Avon Longitudinal Study of Parents and Children, and the Millennium Cohort Study.
4. This research was carried out as part of the CLOSER programme (Cohort and Longitudinal Studies Enhancement Resources). CLOSER aims to maximise the use, value and impact of the UK’s longitudinal studies both at home and abroad. Bringing together nine leading studies, the British Library and the UK Data Service, CLOSER works to stimulate interdisciplinary research, develop shared resources, provide training, and share expertise. In this way CLOSER is helping to build the body of knowledge on how life in the UK is changing – both across generations and in comparison to the rest of the world. CLOSER has £5 million funding from the Economic and Social Research Council (ESRC) and the Medical Research Council (MRC) for the period from October 2012 to September 2017. This funding is made possible by a landmark contribution from the Government’s Large Facilities Capital Fund. Visit www.closer.ac.uk
5. The Economic and Social Research Council (ESRC) is the UK’s largest funder of research on the social and economic questions facing us today. It supports the development and training of the UK’s future social scientists and also funds major studies that provide the infrastructure for research. ESRC-funded research informs policymakers and practitioners and helps make businesses, voluntary bodies and other organisations more effective. The ESRC also works collaboratively with six other UK research councils and Innovate UK to fund cross-disciplinary research and innovation addressing major societal challenges. The ESRC is an independent organisation, established by Royal Charter in 1965, and funded mainly by the Government. In 2015 it celebrates its 50th anniversary.
6. The Medical Research Council is at the forefront of scientific discovery to improve human health. Founded in 1913 to tackle tuberculosis, the MRC now invests taxpayers’ money in some of the best medical research in the world across every area of health. Thirty-one MRC-funded researchers have won Nobel prizes in a wide range of disciplines, and MRC scientists have been behind such diverse discoveries as vitamins, the structure of DNA and the link between smoking and cancer, as well as achievements such as pioneering the use of randomised controlled trials, the invention of MRI scanning, and the development of a group of antibodies used in the making of some of the most successful drugs ever developed. Today, MRC-funded scientists tackle some of the greatest health problems facing humanity in the 21st century, from the rising tide of chronic diseases associated with ageing to the threats posed by rapidly mutating micro-organisms. www.mrc.ac.uk