Poorer teens at substantially greater risk of obesity

More than one-third of U.K. teenagers are starting adult life with excess weight (either overweight or obese), and rates are even higher among the poorest, finds a new study led by UCL researchers.

The research, published today in a briefing paper by the Centre for Longitudinal Studies (CLS) at the UCL Social Research Institute, shows that one in five (21%) young people were obese at age 17, and a further one in seven (14%) were overweight, based on data collected in 2018-19.

In the observational study, researchers found that teens from the poorest families were at the greatest risk, with rates of obesity twice as high among this group compared to those from the richest households (28% versus 14%).

The research analyzed data collected from a nationally representative group of over 10,000 teenagers who have been taking part in the Millennium Cohort Study (MCS) since they were born in 2000-02. Using objective measures of participants' height and weight, the research examined the prevalence of overweight, obesity, normal weight and also underweight among the cohort, from ages three to 17. The findings are based on calculating participants' BMI (weight divided by height squared).

The MCS data shows that rates of obesity have been high among this generation throughout their formative years, with around one in 10 measuring as obese from ages three through to seven, rising to two in 10 from age 11 onwards. At age 17, just over 21% of the cohort was obese, with little difference in obesity levels between males and females.

Obesity rates among teenagers were strongly linked to household income, with those from the least well-off households the worst affected. Using income at birth as an indicator of socioeconomic status, the research showed that levels of overweight and obesity were higher among poorer children across the whole of childhood, and this socioeconomic gap became more pronounced as the cohort moved through adolescence.

Levels of overweight remained broadly stable between ages 14 and 17, at around 14% at both ages, and were similar in different household income groups.

Report co-author Professor Emla Fitzsimons (UCL Centre for Longitudinal Studies) said: "It's a major concern that so many young people are an unhealthy weight and are starting off adult life facing an increased risk of greater long-term physical and psychological health problems. Levels of obesity among this generation are alarming, and are even more worrying given emerging evidence on links between excess weight and COVID-19."

Report co-author Dr. David Bann (UCL Centre for Longitudinal Studies) added:

"Obesity rates in the U.K. have been a concern for decades and these high levels among 17-year-olds, affecting the disadvantaged most, suggest that previous policy initiatives haven't worked.

"Without ambitious policy action, we expect this concerning trend to continue in future and have long-term health consequences. Action on obesity now will help to protect the NHS in future. The planned closure of Public Health England leaves us with a pressing need for an independent properly funded organization which has obesity strategy as part of its remit."

The findings in this study are based on calculating cohort members' BMI. This is widely used as a simple and reliable way of finding out whether a person is a healthy weight for their height. However, it is possible that some cohort members were misclassified as being overweight or obese due to high lean (muscle) mass levels instead of high fat mass levels.