Tag Archives: Obesity

Girls growing up – questions of early puberty

The early onset of puberty in girls has been linked with better bone health in older women, but it is also associated with a host of negative outcomes including teenage pregnancy and serious ill health in mid-life. With girls over the last few decades starting their periods earlier and earlier, this is a real cause for concern. A better understanding is needed of who is affected and how if this trend is to be reversed and the long-term health of girls and women is to be secured. Researchers at the ESRC International Centre for Lifecourse Studies at UCL have investigated whether a girl’s socioeconomic background or ethnicity are associated with early puberty and have looked in detail at more commonly supposed links with weight and stress. Yvonne Kelly explains more.

Sexual activity whilst still young, teenage pregnancy, mental health problems, heart disease and breast cancer later in life are just some of the things linked to early puberty in girls. Over the last few decades, girls have started their periods earlier and earlier (in 2016 at around age 11, according to the NHS).

This research is the first to look over time at whether and how a girl’s social and economic circumstances and her ethnicity might be linked to the early onset of puberty. We suspected that any link that did emerge would, most likely, be explained away by other factors such as being overweight or suffering from stress.

Using information on 5,839 girls from the Millennium Cohort Study, which has been tracking the lives of nearly 20,000 children born at or around the start of the century, it was possible to know, at age 11 whether they had started their period or not.

Details of their birth weight, ethnicity, family income when they were aged 5 and height and weight when they were 7 were also available. This rich information gathered across 11 years of the girls’ lives really enabled us to put together a detailed picture over time of how these factors come together to influence the early onset of puberty.

The girls’ mothers completed questionnaires any social or emotional problems their daughter might be facing, and their own mental health.

Puberty facts and figures

Nearly one in ten of the girls, a total of 550, had started their period at age 11, with girls from the poorest families twice as likely as their most well-off peers to have done so (14.1 per cent v 6.8 per cent). Those from the second poorest group were also nearly twice as likely to have started their period.

Indian, Bangladeshi and Black African girls were most likely to have started their period at age 11, with Indian girls three and a half times more likely than their White counterparts to have done so.

Other factors

On average, girls who were heavier at age 7 and suffered stress in early childhood were more likely to have begun menstruating. Those who had started their periods early also tended to have mothers with higher stress levels, were from single parent families, and tended to have had some social and emotional difficulties themselves.

However, even when we took all these things into account, girls from the poorest and second poorest groups were still one and a half times more likely to have started their periods early.

As far as ethnicity was concerned, income, excess body weight and stress accounted for part or all of the differences in most cases. Interestingly, though with most Indian girls coming from more advantaged backgrounds than their White peers, the likelihood of them having started their period was not explained after we took all the above factors into account.

Lived experiences

Our findings highlight the different lived experiences of ethnic minority groups in the UK: for example Indians are relatively advantaged whereas Pakistanis tend to be materially disadvantaged, Bangladeshis and Black Africans are materially and psychosocially disadvantaged and have a tendency to be overweight compared with the majority ethnic group. They also demonstrate the complex and potentially opposing factors at play for the onset of puberty.

All that considered, we can say with considerable confidence that socioeconomic and ethnic disparities are indeed apparent in the UK. Given the short and long term implications for early puberty on women’s health and well being, improving our understanding of these underlying processes could help identify opportunities for interventions with benefits right across the lifecourse, not just for the girls in our study, but for future generations.

It was also encouraging to note that in the decade or so covered by the data we used, there appears to have been no further decline in the average age that girls begin puberty.

Early puberty in 11-year-old girls: Millennium Cohort Study findings is research by Yvonne Kelly, Afshin Zilanawala, Amanda Sacker, Robert Hiatt andRussell Viner and is published in Archives of Disease in Childhood.

Photo credit: Afla

Born in Bradford

Born in Bradford is a fascinating child health development project following the lives of thousands of children in the city. It hopes to find out more about the causes of childhood illness by studying children from all cultures and backgrounds as their lives unfold.

In this Child of our Time Podcast episode, one of the project’s lead researchers, Professor Kate Pickett from the University of York, explains more about the study, what’s in it that researchers can use, what  it’s found so far and what we can expect to come out of it in the future.

Photo credit: Tim Green

Giving children a better start

Child of our Time Editor, Yvonne Kelly will today be discussing why poorer children are more likely to be obese than their better off peers at a Big Lottery Fund event looking at how to give young children a better start in life.

She will be sharing recent research from the team at the ESRC International Centre for Lifecourse Studies at UCL looking at patterns of obesity in  young children using data from the Millennium Cohort Study.

The research finds that children from poorer backgrounds are the most likely to be obese and that the inequalities between richer and poorer children increase over time (between the ages of 5 and 11).

The research also identifies a number of other important factors associated with childhood obesity including smoking during pregnancy, mother’s obesity, skipping breakfast and irregular bedtimes.

The event, A Better Start ‘Focus on Diet and Nutrition is part of a programme of evaluation of the Lottery Funded ‘A Better Start’ initiative which aims to improve the life chances of babies and very young children by delivering a significant increase in the use of preventative approaches in pregnancy and first three years of life.

Yvonne is one of a group of experts and innovators in the field of child health and development to be invited to participate in the first of the initiative’s Learning and Development events. Other speakers include Eustace de Sousa, the lead for children, young people and families at Public Health England and Michael Hallsworth, director for Health at the Government’s Behavioural Insights Team, Chris Cuthbert, Director of the Big Lottery Development Fund and Celia Supiah, CEO of the charity Parents 1st.

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

 

 

Teenage obesity and bowel cancer risk

Bowel cancer is the third most common cancer among men worldwide, with nearly 1.4 million new diagnoses each year. Links with obesity in adulthood are fairly well established with what appears to be a rise in risk with increasing body mass index. The link is significantly stronger for men than it is for women. Much less is known about potential causes at earlier stages of life, especially adolescence, as Professor Scott Montgomery from UCL explains.

Adolescence marks the transition from childhood to adulthood and is a period of accelerated growth, especially for men. We wanted to look at whether obesity, or even just excess weight, during the teenage years increase the likelihood of colorectal cancer later in life?

Asking men diagnosed with bowel cancer what they weighed as teenagers is not a reliable source of data. What we needed to examine this question robustly was a large sample of men who were accurately measured in their youth and are now sufficiently old for a significant number to have developed bowel cancer.

One such group is men who experienced compulsory Swedish military conscription assessments. Around a quarter of a million young men aged around 18 years were assessed for conscription between 1969 and 1976. After excluding those with errors in the original measurements and excluding men with pre-existing medical conditions gave us a sample of just under 240,000 – equivalent to 8 and half million person years of data.

The men’s height and weight was measured by trained personnel during the conscription examination. From these data body mass index (BMI) or kg/m² was calculated and those numbers were put into five groups – underweight (BMI of less than 18.5), normal (BMI of 18.5 to 24.9), lower overweight (BMI of 25 to 27.4), upper overweight (BMI of 27.5 to 29.9) and obese (BMI of over 30).

A blood test was also taken and tested for signs of higher levels of inflammation, which can signal diseases processes relevant to bowel cancer risk.

Cancer diagnosis

Over an average of 35 years following conscription, 885 of the men were diagnosed with bowel cancer, comprising 501 cases of colon cancer and 384 cases of rectal cancer.

Men who had been underweight in adolescence had a slightly lower risk of a colorectal cancer diagnosis than normal weight men. Lower overweight men had a non-statistically significant higher risk, upper overweight men had a statistically significant 2.08-fold higher risk and obese men had a 2.38-fold higher risk.

Men, who had suffered high levels of late adolescent inflammation, were found to be at a 63% higher risk of being diagnosed with bowel cancer than those with normal levels. The link between BMI and a diagnosis was independent of inflammation levels, suggesting adolescent BMI may be operating in a different way and through mechanisms other than the inflammation detected during adolescence.

The average age at the end of follow-up was 53.9 years, so our analysis did not look at any changes in late adulthood. It seems unlikely, though, that the upper weight groups would suffer less in later years.

It was also impossible to account for whole life measures of BMI and inflammation and so we are not able to comment on whether the strong association between adolescent BMI and bowel cancer could be mitigated by weight loss during adulthood. It is, however, plausible that it is the total duration of exposure to high BMI or inflammation that brings the increased risk rather than exposure at a specific age. High BMI or inflammatory processes already present during adolescence may persist for many years into adulthood.

It is also important to stress that the findings do not necessarily apply equally to women. Certainly, other studies have shown the associations between BMI and inflammation and bowel cancer are weaker among women than men.

Robust study

All that said, this is a robust, important study based on good quality measurement and a lengthy time frame. At a time when increasing adolescent obesity in the United States, for instance, appears to be being followed by an increasing incidence of bowel cancer among young adults, it contributes to the case for further work to be undertaken with some urgency.

What our research does suggest is a graded association between adolescent inflammation and bowel cancer and an even stronger association between adolescent BMI and the risk of bowel cancer in men. We have notable evidence of a link between these exposures at a particularly vulnerable stage of development and the later incidence of bowel cancer.

More work needs to be done, particularly to clarify how inflammation and BMI act or interact to affect an increased risk of bowel cancer. Further research is also needed to disentangle these factors from other risks both in adolescence and later life.

Further information

Adolescent body mass index and erythrocyte sedimentation rate in relation to colorectal cancer risk is research by Elizabeth D Kantor, Ruzan Udumayan, Lisa B Signorello, Edward L Giovannucci, Scott Montgomery and Katja Fall and is published in the journal, Gut.

Photo credit: Marina Lobanova

Are children becoming obese earlier?

Are children becoming obese at a younger age compared with the generations before them? New evidence from a research team at CLOSER, making use of the UK’s Cohort Studies, indicates they are. One of the team, Professor Rebecca Hardy from UCL, spoke to Child of our Time about the research.

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, is research by William Johnson,  Leah Li,  Rebecca Hardy and Diana Kuh, and is published in PLOS Medicine.

Child of our Time podcasts are produced by Research Podcasts.

Photo credit: Bill Gracey

Ethnicity, birthweight and growth in early childhood

Birthweight varies according to ethnic group but height at the age of five does not. Why might that be? Does it tell us anything about the lives of second and third generation immigrants? And does it offer any useful guidance to health professionals hoping to target disadvantaged groups? Professor Yvonne Kelly outlines recent research with colleagues at the ESRC International Centre for Lifecourse Studies looking at differences in birthweight and early growth between ethnic groups.

Birthweight is important. There is a large body of work that suggests links between low birthweight and the development of chronic disease. Height at the age of five is a less straightforward indicator but still an important measure. The relationship between the two is important as well. Rapid post-natal growth may also have a role in later disease risk, and any correlation may tell us something about the lives of people born in the UK to parents born elsewhere.

Earlier research shows that babies born to South Asian and Black mothers weigh up to 300g less than those with White mothers. They are also up to two and a half times more likely than their White counterparts to have low birthweight.

Our study made use of the rich information available in the Millennium Cohort Study and enabled us to drill down further into ethnic differences. We were able to look at White, Indian, Pakistani, Bangladeshi, Black Caribbean and Black African groups.

These, of course, are groups that have very different migration histories. The Black Caribbeans and Indians mainly migrated to the UK in the 1950s and 1960s. The Pakistanis arrived in the 1960s and 1970s, the Bangladeshis in the 1980s and the Black Africans in the 1990s.

Social v biological

If you accept that ethnicity is a social not a biological construct, these variations must be the result of factors that are not intrinsic to the group but tend to go with membership. Relevant factors are likely to be either socioeconomic or maternal.

So, if one group tends to have higher incomes and higher levels of educational attainment, it is likely to have fewer babies with low birthweight. Similarly, if mothers within one group are less likely to smoke they too are likely to have heavier babies.

Because our research compared data on birthweight to those on ethnicity, socioeconomic status and maternal characteristics, it was possible to identify which were most closely associated.

The results suggest that socioeconomic factors are important in explaining birthweight differences in Black Caribbean, Black African, Bangladeshi and Pakistani infants. Maternal characteristics are important in explaining birthweight differences in Indian and Bangladeshi groups. Clearly, both must operate to some extent in all cases.

Our study identifies the dominant factor for each ethnic group and recommends policy-makers pay attention to the different socioeconomic and culturally related profiles of ethnic minority groups when devising policies aimed at reducing inequalities in birthweight.

A question of height

One key maternal characteristic identified was height. Mothers from the Indian, Pakistani and Bangladeshi groups were on average 8cm shorter than White mothers. We speculate that it might take several generations for individuals within ethnic groups to reach their height potential.

And it could be that increases in maternal height do not happen so much for the first couple of migrant generations due to the ‘accumulated effects of disadvantage, including racism, discrimination and poverty that are disproportionately experienced by migrants’. That idea was put to the test in a second study also using MCS data.

The primary aim of this research was to investigate ethnic differences in height at 5 years of age. The same ethnic groups were used. Again, the sample was large and broadly representative of the whole UK.

Playing catch up

In contrast to the findings on birthweight, Indian, Pakistani, Black Caribbean and Black African children were taller than White children at age 5. Bangladeshi children were the same as White children. Birthweight was not entirely irrelevant. It was a weak to moderate predictor of height in White, Pakistani, Bangladeshi and African children.

All the measured variables favoured the White group over all ethnic minorities. This is consistent with the suggestion floated towards the end of the first study that what is happening is that a generation is ‘catching up’, earlier generations having been previously thwarted by such factors as poor nutrition in underdeveloped home countries.

Saying that, catch-up growth is likely to explain only a part of the ethnic height differences identified and further research is important here. It is also important to note that taller children are more inclined to obesity and so the height advantage of ethnic minority children might not translate into a health advantage in adulthood.

The links between ethnicity, birthweight and height in childhood are not, then, straightforward or by any means fully understood. It is clear that outcomes associated with different groups are the result of social and not biological characteristics.

The length of time a group has been established in the UK also appears to play a part with at least some suggestion of a generational ‘catch-up’ effect. Though there may be plenty of inequality left to address, that does at least suggest things are moving in the right direction.

Further information

Why does birthweight vary among ethnic groups in the UK? Findings from the Millennium Cohort Study is research by Yvonne Kelly, Lidia Panico, Mel Bartley, Michael Marmot, James Nazroo and Amanda Sacker and is published in the Journal of Public Health.

Ethnic differences in growth in early childhood: an investigation of two potential mechanisms is research by Amanda Sacker and Yvonne Kelly and is published in the European Journal of Public Health.

Photo credit: moinuddin forhad

[1] Ethnic differences in growth in early childhood: an investigation of two potential mechanisms. A. Sacker, Y. Kelly

Get up, get out, get active!

Just what are the long term effects of being a couch potato as a youngster? New research using the  1970 British Cohort Study shows we may reap what we sow if we don’t switch off the television or the Playstation and get ourselves and our kids off the couch and active. Dr Mark Hamer from UCL spoke to Child of our Time about the research.

“Childhood correlates of adult TV viewing time: a 32-year follow-up of the 1970 British Cohort Study”, by Lee Smith, Ben Gardner and Mark Hamer of UCL’s Department of Epidemiology and Public Health. It will be published in a future issue of the Journal of Epidemiology and Community Health.

Child of our Time podcasts are produced by Research Podcasts.

Photo credit: NelsonNZ

Middle-aged couch potatoes ‘planted’ 30 years earlier

Parents should routinely switch off the TV and take young children out for a walk or some other exercise in order to increase their chances of growing up to be fit, healthy adults, new research suggests.

And if it isn’t feasible to go outside, children could perhaps be encouraged to play interactive video games that involve physical activity.

Researchers at University College London have reached these conclusions after comparing the TV viewing habits of more than 6,000 British people at age 10 and age 42.

The study revealed that children who watched a lot of TV at age 10 were much more likely to spend more than three hours a day in front of the screen at age 42 than those who had watched relatively little television in childhood.

Eighty-three per cent of the 1,546 cohort study members who reported watching more than three hours of TV at 42 had also watched TV “often” at age 10.

The study also showed that 42-year-olds who watched TV for at least three hours a day were more likely to be in only “fair” or “poor” health and to report that they were either overweight or obese.

They were also more likely to have had fathers who were overweight and in routine or manual jobs at the age 10 survey. The sons and daughters of manual workers were, in fact, twice as likely as managers’ children to watch more than three hours of TV a day at 42, even after their own educational qualifications had been taken into consideration.

The researchers analysed information collected by the British Cohort Study, which is following the lives of people born in England, Scotland and Wales in the same week of 1970. The cohort study is managed by the IOE’s Centre for Longitudinal Studies (CLS) and is funded by the Economic and Social Research Council.

“The problems that we have identified are not experienced exclusively by working-class families,” Dr Mark Hamer, one of the UCL researchers, will tell the CLS research conference in London today (March 16).

“However, parents from a lower socio-occupational class are more likely to be physically active at work and may compensate for this by spending more time sitting down during their leisure hours. Their children may then model their mothers’ and fathers’ leisure activity patterns.

“It is important that children keep active. And if they can be encouraged to participate in sports, so much the better.”

Previous research has suggested that parental participation in physical activity may be a predictor of childhood activity levels. The UCL study is, however, believed to be the first to use a large, representative birth cohort to identify childhood factors that are associated with television viewing habits in middle age.

“Our work indicates that parents’ health-related behaviours may at least partly influence children’s TV viewing habits more than three decades later,” Dr Hamer says. “This has important implications for policy and practice.

“It suggests that interventions to reduce passive TV viewing time should target children and their parents. Such initiatives could not only help today’s children but help to reduce passive TV viewing in future generations.

“That could be extremely beneficial as research has also shown that TV viewing is associated with other health-risk behaviours, such as the consumption of energy-dense foods and cigarette smoking. Prolonged TV viewing has also been linked to type 2 diabetes and cardiovascular disease.”

The paper that will be presented at the CLS conference is “Childhood correlates of adult TV viewing time: a 32-year follow-up of the 1970 British Cohort Study”, by Lee Smith, Ben Gardner and Mark Hamer of UCL’s Department of Epidemiology and Public Health. It will be published in a future issue of the Journal of Epidemiology and Community Health.

Photo credit: clarkmaxwell

What teenage girls eat

Teenage girls have the poorest diets of all according to the National Diet and Nutrition Survey with less than one in ten girls eating the recommended five-a-day fruit and vegetables.

At an ESRC International Centre for Lifecourse Studies Policy Seminar, researcher Laura Weston presents preliminary evidence from NatCen Social Research on adolescent girls’ nutrient intake and the factors that influence it.

Photo credit: Magdalena O

Further information and links

Read a full transcript of the presentation

National Diet and Nutrition Survey