Tag Archives: Physical Activity

Time to help our children get a move on

 World Health Organisation and United States guidelines say adolescents should do at least an hour’s moderate-to-vigorous physical activity each day. But a new global study shows eight out of 10 fail to meet that standard – and there is a widening gender gap. Professor Yvonne Kelly and Fran Abrams outline new research revealing worrying trends which demonstrate the need for political and social choices that will help young people enjoy the social, physical and mental benefits of being active.

Physical activity has many health benefits for young people – and globally,  four in every five adolescents do not benefit from regular physical activity.

 In 2018, the WHO launched a global action plan called More Active People for a Healthier World. It aimed to reduce the proportion of people doing insufficient physical activity by 15 per cent by 2030 among both adolescents and adults. 

Now in a major new study WHO researchers have analysed information on 1.6 million school students aged 11-17 in 146 countries. They found some positive trends but argued much still needed to be done to encourage young people to exercise more.

There was a small reduction over 15 years in the proportion of boys not doing enough, though this still fell well short of the WHO’s target. But the proportion of girls meeting the target remained static and this led to a widening gender gap. 

As has been shown in the UK such gender differences start early with lower levels of physical activity in girls emerging before they become teenagers. 

The authors of a separate investigation using the Millennium Cohort Study (MCS) suggest the main reason for young people not exercising or sleeping enough is the amount of time they spend using screens. This is a hotly contested area, intuitively, ‘too much screen time’ and ‘too little exercise’ might appear to sit side by side.  However, in this kind of study, it is not possible to infer that one causes the other. 

The WHO study showed the majority of adolescents did not meet physical activity guidelines, putting their current and future health at risk. Although there were small reductions in insufficient activity among boys, the prevalence of insufficient physical activity in girls had remained unchanged since 2001.

 

Figure 1 Prevalence of insufficient physical activity among school-going adolescents aged 11–17 years, globally and by World Bank income group, 2001 and 2016

Huge dataset

The dataset used in the WHO study was huge – the young people studied had provided information for at least three years and the analysis covered four World Bank income groups, nine regions, and the globe as a whole for the years 2001–16. Saying that, although  the research data covered more than 80 per cent of the global population, it still didn’t cover every county and region. And the estimates for low-income countries need to be treated with caution as the coverage there was much lower – only 36 per cent.

The overall analysis showed that more than eight out of 10 school-going adolescents aged 11–17 did not meet the recommendations for daily physical activity. The small improvements in boys’ activity levels, combined with the static position in girls’ activity, suggested a target of more than 30 per cent of adolescents meeting the recommended level by 2030 will not be met.

Globally, across all income groups and regions and in nearly all the countries analysed, girls were less active than boys.

And perhaps surprisingly, the research did not find that the problem was worse in higher-income countries. However, this was not the case for girls, for whom there was no clear pattern in relation to country income.

Differences in activity levels

In addition to variations related to gender and affluence, there were also differences in activity levels between different parts of the world. The boys least likely to meet activity targets were in the high-income Asia Pacific region, but the second-least likely were in lower-income Sub-Saharan Africa and particularly in Sudan and Zambia. 

The boys most likely to meet the targets were found in high-income western and south Asian countries with large populations such as the USA, Bangladesh, and India.

These variations might be driven by specific characteristics of particular countries – for example, as the research looked at school children the picture might be skewed in countries where disadvantaged children often do not attend school, or in places where the tradition of school or community sport is strong.

For girls, the largest proportions failing to meet the targets were in Asia Pacific and particularly in South Korea- though in some of those countries girls’ participation in education is low and that might have affected the study’s sample.

The recent MCS study by academics from Loughborough University and University College London used data from 3899 adolescents. This study, in which young people were fitted with activity monitors, found that while nine out of 10 were getting the recommended amount of sleep, just four in ten met exercise targets and a quarter were keeping to the recommended screen time. These figures were higher than those in the WHO study, which could be explained by the different methods used to measure activity and which show just how important it is to consider HOW activity is measured.

The study looked at  some correlates of physical activity and showed that adolescent girls who had depressive symptoms were less likely to meet all three of these recommendations (8-10 hours of sleep, no more than two hours of screen time and at least an hour a day of physical activity), while those from better-off backgrounds were more likely to meet them. Among boys, those who were obese and those who had depressive symptoms were less likely to meet the recommendations. However, it is not possible to rule out the potential for cyclical associations to be at play here as low levels of physical activity could lead to depressed mood and to weight gain.

What can be done? 

  • More research is needed to understand the causes of non-participation in exercise – social, economic, cultural, environmental and technological. 
  • Policy change should be prioritised and should encourage all forms of physical education – sport, active play, and recreation as well as safe walking and cycling.
  • Social marketing campaigns such as the National Lottery funded #thisgirlcan campaign combined with community-based interventions could be starting points to increase physical activity levels in girls, particularly in countries with wide gender differences. This approach has been identified as cost-effective.
  • Schools, families, sport and recreation providers, urban planners, and city and community leaders all need to become involved.

That four in every five adolescents do not experience the enjoyment and social, physical, and mental health benefits of regular physical activity is not a chance thing – it is the consequence of political  choices. 

Young people have the right to play and should be provided with the opportunities to realise their right to physical and mental health and wellbeing. Urgent action is needed, particularly through targeted interventions to promote and retain girls’ participation in physical activity. Policymakers and stakeholders should be encouraged to act now for the health of this young generation and of future ones.

Yvonne Kelly is Professor of Lifecourse Epidemiology and Director of the ESRC International Centre for Lifecourse Studies at UCL. She is editor of the Child of our Time blog.

Fran Abrams is CEO of the Education Media Centre and freelance journalist who writes for the Child of our Time blog.

Global trends in insufficient physical activity among adolescents: a pooled analysis of 298 population-based surveys with 1·6 million participants, by Regina Guthold, Leanne Riley, Fiona Bull and Gretchen Stevens, is published in The Lancet Child and Adolescent Health.

Regina Guthold, Leanne Riley and Fiona Bull are based at the Department for Prevention of Noncommunicable Diseases, WHO, Geneva, Switzerland and Gretchen Stevens is at the Department for Information, Evidence and Research, WHO, Geneva, Switzerland.  Fiona Bull is also affiliated with the Department of Sport and Exercise Science, University of Western Australia, Perth.

Prevalence and Correlates of Meeting Sleep, Screen-Time, and Physical Activity Guidelines Among Adolescents in the United Kingdom, by Natalie Pearson, Lauren B Sherar and Mark Hamer, is published in JAMA Paediatrics: 

Natalie Pearson and Lauren Sherar are at the School of Sport, Exercise & Health Sciences, Loughborough University, United Kingdom, and Mark Hamer is at the Institute of Sport Exercise & Health, Division of Surgery & Interventional Science, Faculty of Medical Sciences, University College London, United Kingdom.

Active children

Might population-wide increases in physical activity reduce socio-economic inequalities in the proportion of children who are overweight?

Just half of children in the UK achieve the World Health Organisation’s targets for daily activity, and in England the Government has set its own strategy to tackle this. But would increased physical activity lead to fewer children being overweight or obese? And would it help to address social inequalities in the proportion of children who are overweight? Research from Anna Pearce and colleagues at the UCL Great Ormond Street Institute of Child Health in London suggests more physical activity is unlikely to reduce the prevalence or inequalities in levels of overweight.

Childhood overweight is an important public health problem, with particularly high levels in children living in disadvantaged circumstances. Physical activity is an important determinant of childhood overweight. The World Health Organization (WHO) recommends children should undertake 60 minutes of moderate-to-vigorous physical activity every day. But for many families in England, as in other high-income countries, this is an aspiration rather than the reality.

The UK Government has identified a number of strategies to increase activity among children.  But the potential for physical activity initiatives to help children achieve a healthy weight, if scaled up at the population level, hasn’t previously been assessed. In our research, we focused on the WHO target, and on the likelihood that achieving this will reduce socio-economic differences in levels of overweight or obesity.

We wanted to know how hypothetical government interventions to increase activity might reduce the prevalence and inequalities in childhood overweight at age eleven. Could population-wide interventions, aimed at all, or targeted interventions with high-risk groups, have the greatest effect?

What, specifically, might happen to the prevalence and social distribution of childhood overweight if all children achieved the WHO’s target of 60 minutes’ activity per day? What if we are only able to achieve smaller increases in activity than those required to meet the WHO target?

In our study, 27% children were overweight at age eleven. We found that hypothetical universal interventions to increase physical activity could lead to moderate reductions in this. For example, if 95 per cent of children met the target of 60 minutes of activity per day, the prevalence of overweight (including obesity) would drop to 22 per cent. But more realistic scenarios, in which interventions led to more moderate improvements in physical activity levels (of only a few minutes each day), would achieve only small reductions in overweight within the population.

Children from the most affluent backgrounds were less likely to be overweight  – around one in five children in the top fifth of household incomes were overweight or obese at 11y, compared to one in three among those in the bottom fifth of household incomes. Our analysis suggested these stark social differences in overweight are unlikely to be reduced through meeting the WHO physical activity target. This is partly because children from the highest income group had the lowestlevel of daily activity, with a median of 59 minutes’ moderate to vigorous activity compared 62 minutes for the lowest fifth of the income range.

Even more intensive intervention scenarios, given only to high-risk families (for example those who were overweight or obese at an earlier age, or those living in disadvantaged neighbourhoods), appeared unlikely to address the stark social inequalities experienced by this cohort of children.

Activity targets

The WHO’s physical activity targets are ambitious and, if achieved, are likely to benefit children’s health and wellbeing in a multitude of ways. However our findings suggest that if the Government is serious about supporting children and families – particularly those from poorer backgrounds – to maintain healthy weights, it needs to look elsewhere.

We need, therefore, to know more about how other types of initiatives to reduce childhood overweight might work. Research which aims to inform this debate should look not just at activity levels but also at environmental factors that influence diet, such as taxes on high-sugar foods and foods provided in early-years settings.

What if all children achieved WHO recommendations on physical activity? Estimating the impact on socioeconomic inequalities in childhood overweight in the UK Millennium Cohort Study, by Anna Pearce, Steven Hope, Lucy Griffiths, Mario-Cortina-Borja, Catherine Chittleborough and Catherine Law, is published in the International Journal of Epidemiology, 2019, 134–147.

Anna Pearce is based at the University of Glasgow but carried out this work out in her previous position at the UCL Institute of Child Health.

Steven Hope, Mario Cortina-Borja, and Catherine Law are based at the Population, Policy and Practice Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK.

Lucy Griffiths is based at Swansea University but carried out this work out in her previous position at the UCL Institute of Child Health…

 Catherine Chittleborough is at the School of Public Health, Robinson Research Institute, University of Adelaide, Adelaide, SA, Australia.

This blog is based on independent research funded by the National Institute for Health Research (NIHR) Policy Research Programme (Children’s Policy Research Unit). The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.

 

Off the scales: time to act on childhood obesity

By 2050, it is said that obesity could cost the NHS almost £10 billion a year, with the full economic cost rising from around £27 billion today to £50 billion by then. Today, the Centre for Social Justice (CSJ) publishes its report, Off the scales: time to act on childhood obesity. It calls on the Government to put prevention, health, inequality and cross-departmental collaboration at the heart of its efforts to tackle childhood obesity, drawing particular attention to the need to address the question of why poorer children are at ever greater risk of being obese. It’s a question researchers at the ESRC International Centre for Lifecourse Studies at UCL, including our editor Yvonne Kelly, have been among the first to address.

There have been numerous major studies on childhood obesity over the past 10 years, many of which have shown the links with poverty. But our research looks specifically at why children from disadvantaged families are significantly more likely to be obese than their better off peers.

To examine this as robustly and rigorously as we could, we used data from the Millennium Cohort Study (MCS) which has tracked the lives of nearly 20,000 children from across the UK since the turn of the century. Using a range of measurements taken when the children were aged 5 and 11 together with detailed information about their backgrounds and family circumstances, we were able to demonstrate just how key poverty was in respect of their obesity.

At age 5, poor children were almost twice as likely to be obese compared with their better off peers. By the age of 11, the gap had nearly tripled.

Knowing as we do that obese children are less likely than their peers to grow into economically successful adults and that obesity is clearly linked with a range of chronic diseases, it’s reasonable to say that for these children, the future is far from bright. From a policy perspective it is also clear that unless the gap between rich and poor children can be closed the chances of reducing the overall obesity trend, as the Government states it is committed to doing, are pretty slim.

How is poverty linked to obesity?

The MCS collects a broad range of data, allowing us to dig beneath these headline numbers to tease out some of the specific ways in which relative poverty in childhood leads to an increased risk of obesity.

To examine this question of whether a parent’s own lifestyle might have a role, we looked at factors previously shown to be linked to the increased risk of obesity, such as whether the mother smoked during pregnancy, how long she breastfed for and whether the child was introduced to solid food before the age of four months.

We could also factor in the degree to which a mother was herself overweight or obese and assess children’s physical behaviour, such as how often they exercised, played and how many hours they spent watching TV or playing on a computer, and the time that they went to bed. We looked at whether the child skipped breakfast, how much fruit they ate and how often they had sweet drinks.

A lot of these factors were relevant. A mother’s behaviour when her child was very young was certainly important. Markers of an ‘unhealthy’ lifestyle here could mean as much as a 20 per cent additional risk of obesity for a child.

Obese and overweight children living in poor families were more likely to have mothers who did not breastfeed or breastfed for a shorter duration, who introduced solid foods early in infancy, who smoked during pregnancy, and who were overweight or obese. The poorest children were also more likely to spend more time watching TV and using a PC (and so have greater exposure to food and drink advertising), experience later and more irregular bedtimes, do less sports and be more physically inactive, engage less in active play with their parent, live in an area without a playground, and not have breakfast every day.

5-year-olds from poorer families were also much more likely to gain excess weight up to age 11 than richer children, leading us to conclude that the earlier certain risk factors can be challenged and the appropriate support provided for the least well off families, the greater the chance of positive impact on the risk of obesity and in a reduction in inequality.

Pathways to obesity

More recently we have identified four BMI trajectories for children. The good news is that 80 per cent of them are on a stable path where, on average, from when they’re born through to age 11, they are not overweight.

There is a small group of children who are obese at age 3 but then join the stable group by age 7. We call them the ‘decreasing’ group. There is a ‘moderate increasing group’ (13.1 per cent) where children are not overweight at age 3 but whose BMIs increase throughout childhood into the overweight (but not obese) range. Finally we have a ‘high increasing’ group of children (2.5 per cent) who are obese at age 3 and whose BMI continues to increase.

From an inequality perspective, what’s most striking here is that the wealthiest children are least likely to be in the ‘moderate increasing’ BMI group whilst the poorest children are more than twice as likely to be on the high increasing path.

Today’s CSJ report agrees with our analysis that early intervention is key and, in line with it, proposes three key early years intervention opportunities to ensure children get the healthiest start possible before they reach primary school age.

The report acknowledges that the Government is already trying to persuade families to eat more healthily and take more exercise. But it has joined a body of voices critical of the Childhood Obesity Plan, which, it believes, “fails to put reducing inequality as a goal … despite acknowledging that the childhood obesity burden falls hardest on the poorest children.”

Certainly our body of evidence indicates that policy makers need to acknowledge and address inequality as a root cause of obesity. Doing something about the structural factors in people’s lives is what is needed rather than ‘tinkering around the edges’ of the problem.

Today the CSJ asks why there are disproportionately high levels of obesity, particularly childhood obesity, in our most deprived communities. Our research has gone some way to answering that question, and makes it clear that there is no simple one-stop shop solution.

Obesity is caused by a combination of environmental, biological, cultural and psychological factors, where one factor does not dominate and yet our obsessional search for the ‘one thing’ that can tackle obesity continues. If the Government is going to reduce obesity rates, it will indeed, need to introduce multiple bold measures in tandem across the entire ecosystem and recognise that success may only be measurable after a few years.

Why are poorer children at higher risk of obesity and overweight? A UK cohort study is research by Alice Goisis, Amanda Sacker and Yvonne Kelly and is published in the European Journal of Public Health

BMI Development and Early Adolescent Psychosocial Well-Being: UK Millennium Cohort Study is research by Yvonne Kelly, Praveetha Patalay, Scott Montgomery and Amanda Sacker and is published in Pediatrics

An equal start: longitudinal evidence to support children’s healthy development

Using longitudinal evidence to support children’s healthy development and give them an equal start in life is the subject of our editor Yvonne Kelly’s keynote address at the Growing up in Ireland Annual Conference in Dublin today.

Her talk discusses findings from the most recent of the British ‘birth ‘ cohort studies – the Millennium Cohort Study that have so far informed policy development. They include work by researchers at the ESRC Centre for Lifecourse Studies where Yvonne is based on alcohol consumption during pregnancy, breastfeeding and the introduction of solid foods, the physical punishment of children , childhood obesity, reading to children in the early years, and sleep patterns throughout childhood.

She will also share work with the potential to inform future policy challenges such as young people’s drinking, social media use and mental health.

Ahead of her talk, she said:

“It is well established that what happens in the early years of life has long-lasting consequences for health and social success across the lifespan. Stark social inequalities in children’s health and development exist and emerge early in life. It is therefore crucial to identify potential tipping points and opportunities for intervention   during childhood with the potential to affect change and improve life chances.”

 

 

Screen use at seven: overweight at 11. Why it’s time to say no to a TV in the bedroom for children

Since the launch of the Childhood Obesity Strategy in 2016, there has been much attention focused on the so-called ‘Sugar Tax’. The March 2017 Budget saw confirmation that sugary soft drinks would be taxed in an attempt to combat rising levels of obesity. This is an important move that has been met with widespread approval from public health professionals. Still, obesity is hugely complex and there are many other things at play in addition to the sugary drinks and snacks that children may consume. Researchers at UCL have been looking in detail at different factors associated with obesity and, in a recent paper, find that children who have a television in their bedroom have higher BMI and more body fat than those who do not. Lead researcher, Anja Heilmann, explains the research and why saying no to a TV in the bedroom could be another important strategy in combatting childhood obesity.

As our TV screens have got flatter, our children have got fatter. There is no getting away from it! Screen-based activities play a central role in our children’s lives. At a very young age, they have unparalleled access to television screens, computers, game consoles and a host of mobile devices. Among 5 to 11 year-olds, TV is still the most consumed medium, with gaming coming second.

At the same time, childhood obesity is not just a national, but a global health worry. In 2014/15 a third of 11 year-old children in England were overweight and a fifth were obese.

Research has repeatedly reported a link between TV viewing and obesity, but although some has hinted at the idea that a television in a child’s bedroom might exacerbate the problem, the evidence here has been rather contradictory. Other plausible pathways could include eating unhealthy snacks whilst watching TV, exposure to food advertising and insufficient and poor quality sleep.

Using information from the Millennium Cohort Study (MCS), which has followed the lives of more than 18,000 children born around the turn of the century, we had the opportunity to see whether having a TV in their bedroom when they were age 7 was, in any way, linked with a child being overweight when they were 11 years old. In other words, we wanted to get to grips with whether there were implications over a child’s lifetime of their screen use and if so, what those implications were.

Useful information

Using trained interviewers, the MCS collects a wide range of useful information including the independently measured height, weight and body fat of a child. These provided us with a set of obesity-related measurements: weight, Body Mass Index (BMI) and Fat Mass Index (FMI), a powerful set of measures for overweight and obesity.

When the children were age seven, parents were asked if their son or daughter had a TV in their bedroom, how many hours they spent watching TV or DVDs and how much time they spent playing on a computer.

 At age 7, more than half of the 12,556 boys and girls we looked at in our research had a TV in their room and it was these children who were more likely to be overweight when they turned 11 when we compared them with those without a TV. They were also more likely to have higher BMI and FMI. In total, a quarter of the boys and nearly a third of the girls were overweight at age 11 and the links between having a TV in the bedroom and overweight were stronger for the girls.

Another strength of the research is that we controlled for the child’s BMI at age 3 and maternal BMI, that way adjusting for genetic factors, as well as food environment in the family. We also adjusted for family income and mother’s education – both of which are important as overweight/obesity is socially patterned, as is TV use.

Interestingly, there was no link between overweight and the time a child, whether they were a boy or a girl, spent playing on a computer.

Clear link

So, given the size of our sample and the robustness of the methods employed here, we can say with considerable confidence that there is a clear link between having a TV in the bedroom as a young child and being overweight a few years down the line. For girls, this represents a 30 per cent increase in the risk of being overweight at 11 compared with their peers who do not have one. For boys the risk increases by around 20 per cent.

Another interesting point to note is that the size of this risk or effect is about the same as that of other things shown to be linked with obesity, such as not being breastfed and being physically inactive.

Nevertheless, policy makers looking to create and implement strategies to reduce obesity should certainly consider building access to television screens in children’s bedrooms into their thinking. Specific initiatives focused on young girls could also be important.

Meanwhile, for parents who may consider it a good idea for a young child to have their own TV in their bedroom or feel under pressure to provide one, the message is quite clear: resist the idea and you may be doing even more to set your child on a healthier path into their teenage years and beyond.

Longitudinal associations between television in the bedroom and body fatness in a UK cohort study is research by Anja Heilmann, Patrick Rouxel, Emla Fitzsimons, Yvonne Kelly, and Richard Watt and is published in the International Journal of Obesity.

Be prepared: the mental health benefits of scouting and guiding

Being a scout or a guide when we are young might be a good experience for us in all sorts of ways, but can those positive effects be long lasting though our lives and if so, how? Research using the 1958 Birth Cohort shows a strong link between being a scout or a guide when young and better mental health later in life. Professor Richard Mitchell from the University of Glasgow talks to the Child of our Time Podcast about the research, what he and colleagues from Edinburgh found and what he thinks it tells us.

Photo credit: One-and-Other Girl Guides UK

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Putting a SPRING in the step of mums-to-be

Making sure that mums-to-be are in the best possible health is key to ensuring their baby gets the best possible start in life. But what sorts of things can help them achieve that? In this episode of the Child of our Time Podcast, Professor Hazel Inskip from the MRC Lifecourse Epidemiology Unit at the University of Southampton, talks about an ongoing trial making use of healthy conversations and Vitamin D supplements to try to improve the diet of just pregnant women.

Photo credit: Pregnant, Frank de Kleine

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Sugar-coating the childhood obesity problem

Child obesity figures appear to be on the rise again, causing much concern after earlier signs they had levelled off.  The proportion of  10- and 11-year-olds who were obese in 2015-16 was 19.8 percent, up 0.7 percent on the year before. There was a rise of 0.2 percent among four- and five-year-olds. The announcement comes as researchers at the ESRC International Centre for Lifecourse Studies at UCL have been looking in detail at how and when children become overweight. The team has also been asking whether children who are overweight are more likely to go on to smoke and drink alcohol and if their mental health suffers as they become adolescents. Yvonne Kelly explains the research findings, and considers their implications for the Government’s recent strategy for tackling the childhood obesity epidemic.

The Government’s much-awaited and much-debated childhood obesity strategy was published in August. In the end, it was less comprehensive than had been anticipated, less draconian too. It focuses on two things – reducing sugar consumption and increasing physical activity. But will it be effective in reversing this worrying obesity trend among our children?

It’s fair to say we don’t fully understand what things influence whether, when and why a child might become overweight. Research to date has shown three distinct weight pathways for children: a healthy BMI throughout childhood; becoming overweight during childhood and being overweight/obese throughout childhood.

Previous research has also shown that the child’s mother’s weight, smoking in pregnancy, mental health and other social and economic factors have some link to childhood obesity. But the evidence is far from complete and, where a child’s own mental health is concerned, it’s not at all clear which way the association works.

To try to get a clearer picture of all these things, our research looked at the BMI paths of the participants in the Millennium Cohort Study, which has tracked the lives of nearly 20,000 children born between 2000-2002. We used data collected at birth, 9 months, age 3, 5, 7 and 11.

Once we had established who was on which BMI path, we were able to look at what factors were at play in their lives and to see whether a tendency to overweight and obesity was an indication that a child would go on to face mental health difficulties in early adolescence or start smoking and drinking.

Four pathways to obesity

The BMI data for the 17,000 children we were able to look at for our study showed four distinct groups of children. More than 80 per cent of them stayed on an average non-overweight path throughout their childhood – we call it the ‘stable’ path. There was a small group (0.6 percent) of children who were obese at age 3 but were then in the stable group by age 7. We call them the the ‘decreasing’ group. There was a ‘moderate increasing group’ (13.1 percent) where children were not overweight at age 3 but whose BMIs increased throughout childhood into the overweight (but not obese) range. Finally we had a ‘high increasing’ group of children (2.5 percent) who were obese at age 3 and whose BMIs continued to increase.

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Girls were 30 percent more likely to be in the ‘moderate increasing’ group than boys and were half as likely to be on the ‘decreasing’ path. Indian, Pakistani and Black African children were up to two times more likely to be on the ‘moderate increasing’ path whilst Pakistani, Black Caribbean and Black African children were up to three times more likely to belong to the ‘high increasing’ group.

The wealthiest children were least likely to be in the ‘moderate increasing’ BMI group and children of mums who smoked during pregnancy were up to two times as likely to belong to increasing BMI groups. Children with overweight mums were most likely to be on the moderate and high increasing paths.

Children on the moderate and high increasing paths were less likely to have regular family routines – they were more likely to skip breakfast or have non-regular bedtime schedules. Interestingly, however, no strong links emerged with some of the things more readily linked with childhood obesity such as sugary drinks and snacks, watching TV and lack of physical activity such as sports, the main focus of the newly published childhood obesity strategy.

Overweight factors

So it seems quite a large range of factors influence the likelihood of a child becoming overweight or obese over the first decade of their life. On top of this, being overweight or obese would also seem to point to a less happy and fulfilling early adolescence and a tendency to explore risky behaviours like smoking and drinking.

Although our research did not show a clear link with sugary drinks and snacks, there are nevertheless some compelling arguments for reducing the sugar intake of our children. These are not only related to problems of obesity, but to wider issues including the major issue of tooth decay and associated emergency hospital admissions. There is also increasing evidence of the ‘addictive’ nature of sugar with research suggesting that it stimulates a sort of ‘reward path’ in certain centres of the brain meaning that the more we have the more we want. It has been shown that people who reduce their sugar intake tend to crave it less.

Where sugar taxes have been introduced in other countries (Mexico, France, Denmark, South Africa amongst others), the intervention has been shown to help reduce the consumption of sugary drinks. As yet, there is no evidence that it helps reduce BMI and tackle obesity, but it’s argued it will take time for us to see an effect on whole populations.

Disadvantaged families

It is hard to predict how much impact the voluntary rather than mandatory reduction in sugar content of drinks and snacks agreed in the strategy will have. As for the sugar tax that will be introduced in two years’ time, there remain concerns that disadvantaged families more likely to purchase and consume sugary goods than their better off counterparts will be hardest hit. Policy makers will need to think hard about how any negative consequences of this might be counteracted.

Our research shows clearly that when it comes to the likelihood of a child becoming overweight or obese in the first decade of their life, there are many more influences than just sugar. Those influences are at play in families even before our children are born.

Helping pregnant women to stop smoking and maintain a healthy weight, making sure all young children have healthy eating and sleeping routines would seem to be key, together with targeted support for the ethnic and social groups identified as being most at risk.

Further information and resources

BMI development and early adolescent psychosocial well-being: UK Millennium Cohort Study is research by Yvonne Kelly, Praveetha Patalay, Scott Montgomery, and Amanda Sacker. The work, published in Pediatrics, is funded by the Economic and Social Research Council.

Media coverage

Photo credit: Kim Stromstad

Why poorer children are at greater risk of obesity

Obesity may be the biggest public health crisis facing the UK today. Levels have risen more than three fold since 1980. Being obese makes you vulnerable to a range of health risks. Being an overweight child makes it more likely you will become an obese adult. And you are much more likely to be an overweight child, if you come from a poor family. If current trends continue, half the population of Britain could be obese by 2050. Early intervention is the most effective way to break this cycle. And that requires a better understanding of why children become overweight. A new study by a team at the ESRC funded International Centre for Lifecourse Studies in Society and Health at UCL and LSE makes clear the scale of the problem and points to some crucial factors likely to lead less-well-off children to gain excess weight, as co-author Professor Yvonne Kelly explains.

A link between poverty and childhood obesity has been found in many developed countries. Intuitively, it seems likely this link is the result of poorer parents not being able to afford healthier food, like fruit, or outings involving exercise for their children. It could also be that those parents know less about healthy lifestyles and that they themselves eat less healthily and exercise less. But intuition is an insufficient basis for the scale of intervention required. This study is the first attempt to examine and compare in detail why children in poorer families are more likely to be overweight.

Our data comes from the Millennium Cohort Study (MCS). This tracks nearly 20,000 families from across the UK. We used measurements made when the children were aged 5 (when just entering primary school) and 11 (the point at which they leave primary school and are on the cusp of adolescence). We used standard definitions for ‘obese’ and ‘overweight’.

‘Stark’ link between poverty and obesity

The first thing we found was that the link between relative poverty and childhood obesity is stark. At age 5, poor children were almost twice as likely to be obese compared with their better off peers (6.6% of children from families in the poorest fifth of the sample were obese while the figure for the richest fifth is just 3.5%). By the age of 11, the gap has widened- nearly tripling (7.9% of the poorest fifth are obese; for the best-off, the figure is 2.9%).

Given that obesity is linked to the development of numerous chronic diseases and that there is evidence overweight and obese children are less likely to grow into economically and socially successful adults, this is a significant burden to be borne by the children of the less-well-off. And unless we can weaken the link our chances of reversing the overall obesity trend are much reduced.

Potential causes of that link

The MCS collects a broad range of data, allowing us to dig beneath these headline numbers to identify some of the specific ways in which relative poverty in childhood leads to an increased risk of obesity.

To measure the degree to which the mother followed a healthy life-style we looked at factors previously shown to be linked to the increased risk of obesity, such as whether the mother smoked during pregnancy, how long she breastfed for and whether the child was introduced to solid food before the age of four months.

We could also factor in the degree to which the mother was herself overweight or obese. To assess the impact of physical behaviour, we compared the frequency of sport or exercise, active play with a parent, hours spent watching TV or playing on a computer, journeys by bike and the time that children went to bed. We compared dietary habits via data on whether the child skipped breakfast and on fruit and sweet drink consumption.

Multiple factors

What we found was that a lot of these factors were relevant. Maternal behaviour in early childhood was certainly important. Markers of ‘unhealthy’ lifestyle here could mean as much as a 20% additional risk of obesity for a child. Measures of physical activity and diet were also relevant at both 5 and 11 years of age, as were early bedtimes and fewer hours in front of the TV or games console. Skipping breakfast and eating more fruit were factors at 5 but less significant at 11. Doing sport more frequently played a more important and protective role at age 11 than at age 5.

Further examination of the differences between the children aged 5 and aged 11 revealed that poorer children aged 5 were much more likely to gain excess weight up to age 11 than richer children. The earlier certain lifestyle factors can be challenged, therefore, the greater the chance of positive impact.

Multiple responses

Assuming that income inequality is not going to disappear, we can only tackle ‘inherited’ obesity via the lifestyle choices that tend to go with lower incomes. Early intervention with mothers clearly has huge potential. And evidence from our work suggests that this should start before birth or even conception. It is clear, too, that campaigns to encourage family physical activity and healthier diets would help.

The Government is already trying to persuade families to eat more healthily and take more exercise. But these efforts are widely targeted and their effectiveness only broadly assessed. Our analysis has already suggested better targeting. More research should be undertaken to narrow the aim and increase effectiveness still further.

Why are poorer children at higher risk of obesity and overweight? A UK cohort study is research by Alice Goisis, Amanda Sacker and Yvonne Kelly and is published in the European Journal of Public Health.

Photo credit: Playing on the computer,  John Watson