A third of adults in Wales live with obesity, according to new analysis

A third of adults in Wales (34%) have been revealed to be living with obesity in 2022-23, according to new analysis by Nesta - potentially more than any other nation in the UK - with older generations much more severely affected than previously thought.

The methodology for generating official government statistics on obesity prevalence within the Welsh population is different from that used in the other three nations. Whereas in England, Northern Ireland and Scotland obesity figures are mainly based on measurements taken by health professionals — or when this has not been possible self-reported data has been adjusted to approximate professionally measured data — in Wales the numbers rely on unadjusted self-reported height and weight measurements. 

However, it’s well known that in self-reported cases, people tend to underreport their weight and overreport their height. This skews the body mass index (BMI) calculations used to figure out how widespread adult obesity is across a whole population.

Obesity in Wales has been significantly underestimated

But by applying the same prediction equations used in England and Scotland to correct for bias in self-reported height and weight data, Nesta has found that the Welsh Government has been dramatically underestimating the extent of obesity in Wales.

Making these corrections resulted in estimated adult obesity rates in Wales jumping from 25% in 2021-2022 to 32%. This is considerably higher than figures for that year in both England and Scotland where 26% and 29% of adults were living with obesity respectively. It also means that potentially Wales has higher obesity rates than in Northern Ireland, where 27% of adults were living with obesity in 2019-20 (when height and weight were last asked as part of Health Survey Northern Ireland).

Using the same approach to correct data from 2022-23 — the most recent National Survey for Wales — we found that approximately 34% of adults in Wales were estimated to be living with obesity (compared to 26% on the uncorrected measures). The data for 2022-2023 is not currently available for the other UK nations.