What is behind the local childhood obesity corridor

As part of our new strategy, we plan to tackle childhood obesity in our London boroughs of Lambeth and Southwark over the next five to ten years.

It’s clear why our analysis of the local and national health needs led us to shortlist childhood obesity as a key health issue for our two boroughs.

London itself has the highest rate of childhood obesity of any major global city, according to the London Health Commission. The prevalence of obesity when children are measured at Reception is higher in both Lambeth (11.1%) and Southwark (12.2%) compared to England (9.3%) and London (10.3%). These figures put Southwark fifth and Lambeth in tenth place among London boroughs. This higher prevalence continues at Year 6, with obesity rates reaching 23.2% in Lambeth and 26.7% in Southwark, compared to England (19.8%) and London (23.2%). At this point, Southwark remains fifth in London, while Lambeth, interestingly, drops to 16th place.

Looking beyond the averages

We can learn a lot about the importance of childhood obesity by looking at the rates across our two boroughs. However, these averages mask important variation in the prevalence and causes of childhood obesity both within and across Lambeth and Southwark. When we zoom in, a more nuanced picture emerges.

A more detailed look at data shows that there are local pockets of obesity that are exceptionally high. Camberwell Green, in Southwark, has the highest prevalence of all London wards at Year 6 and second highest prevalence (34%) of the more than 7000 wards in England. Brunswick Park (31.8%), also in Southwark, is not far behind in sixth place in England and fourth highest in London.

This tells us that childhood obesity is particularly severe in parts of Southwark, and we want to do something about it.

In response, and echoing the recent blog by my colleague Sarah Hickey, we think we can have a bigger impact by focusing down to specific neighbourhoods, working with defined communities for a deeper understanding.

Also, certain areas with our boroughs could be an ideal test bed to understand better how to tackle extremely high levels of obesity somewhere urban, hugely diverse and with high levels of deprivation, which is relevant to cities all over the world.

The issues behind the rates

The data also tells us there is significant variation in childhood obesity across the two boroughs. The variation is particularly great in Southwark. Importantly, there is significant variation in the prevalence of the underlying causes of child obesity. For example, Dulwich Village has childhood obesity rates of 12% at Year 6. The area has a median household income of £58,400 and 20.1% Black, Asian and Minority Ethnic (BAME) population. On the other hand, Camberwell Green has 61.1% BAME and average household income of £31,840. There, obesity rates are 34% at Year 6.

Median Household Income by % obesity at Year 6, All London Wards, Lambeth highlighted blue, Southwark highlighted purple

This mixture within the boroughs of high and low levels of obesity (and areas of affluence and deprivation) is why we’ve decided to focus in on a neighbourhood level. One implication, is that we need to be targeted to ensure we’re working where there is genuine need. And, as the opportunities and difficulties with tackling obesity will vary substantially across the boroughs, we will need to tailor our services to the specific local context.

Our obesity corridor

What the data also tells us is that the variation in obesity is not random. There’s a clear corridor that runs across the boroughs.

When mapped against the boroughs’ geography, the outcomes display a clear pattern, running west-east just above the centre of the boroughs. So much in fact that, with rates radiating out of an obesity epicentre around Faraday and East Walworth wards, the pattern looks like that of an infectious disease, with echoes of the Broad Street pump outbreak.

As the National Child Measurement Programme has identified, there is a very clear spatial pattern in the underlying causes of obesity, such as ethnicity and deprivation. What’s more, the spatial patterns of cause and effect overlay very neatly in our boroughs. This holds across a wide variety of indicators including median household income, multiple deprivation score, percentage of people on claiming Job Seekers Allowance, percentage of households social rented, unauthorised absences in schools and turnout at mayoral elections.

This strongly suggests, as noted in a recent report by Professor Paul Plant of Public Health England, that obesity is an inequalities issue.

Left map: Prevalence of obesity among children in Year 6 (age 10-11 years) - 2013/14 to 2015/16
Right map: Median Household income estimate (2012/13)

Complex interactions

The causes of obesity correlate with each other. This makes the impact of any specific factor on childhood obesity hard to measure. The complexity that underlies the issue can been seen by glancing at the Foresight map.

As articulated by Dr Harry Rutter from the London School of Hygiene and Tropical Medicine in a recent article first published in The Lancet, the complex nature of health issues such as childhood obesity is an ongoing problem for public health research and policy. Issues such as childhood obesity involve multiple factors operating over many decades in systems that adapt as changes occur. For example, the distribution of obesity in a population might be impacted by changes to food, employment, transport or economic systems.

As a result, there is no simple or single solution: any activity has to be part of a whole-system approach. The traditional linear approaches to policy and research are not suited to tackling these challenges as they focus largely on changes in individuals, not the population as a whole, and tend to look at isolated interventions rather than the contexts in which they take place.

We hope to address some of these issues by taking a whole-system, cross-sector approach. We want to focus on particular neighbourhoods so we can better understand the drivers and solutions and layer up initiatives to create a concentration of activity around the children and families who live there.

We know that understanding the interaction between people and place is critical to successfully tackling childhood obesity. As child obesity is complex, we think we can better understand the issue by layering evidence from data, practitioner voice and lived experience. We are just at the start of the journey and will continue to learn, joining forces with others to build and share both local and international evidence and expertise.