The public focuses on individual choices, while experts emphasise environmental causes of obesity

This ESRI Research Bulletin summarises the findings from "A mental model of obesity: Comparing expert and public perceptions in Ireland, the UK and the US" by Deirdre A. Robertson, Ylva Andersson, Ciarán Lavin and Peter D. Lunn, is published in the International Journal of Obesity. Available at: https://doi.org/10.1038/s41366-026-02098-z. 

Introduction

Obesity rates have risen sharply over the past 50 years and constitute a major global public health concern. Scientific evidence shows that this obesity epidemic has been driven mainly by environmental and societal factors, such as changes to food production systems, growth in advertising, larger portion sizes and car-dependent neighbourhood design. By contrast, public debates generally focus on individual choices about food and exercise. Understanding how people think about obesity - their "mental model" - is important because it shapes support for different policy responses.

This study compared the public's perceptions of obesity with those of experts in Ireland, the UK, and the US. The goal was to identify gaps between public and expert understanding that may explain differences in support for obesity-prevention policies, while comparing three countries with different trajectories of the obesity epidemic.

Data and methods

We used an online survey of 2,400 adults - 800 in each of Ireland, the UK and the US. Samples were broadly representative of each country's population. Participants completed a series of tasks designed to assess perceptions of the causes of the obesity epidemic, beliefs about who is responsible for tackling it, knowledge of obesity prevalence and related health consequences. Support for a range of obesity policies was also assessed, including informational campaigns; taxes and restrictions on the fat, salt and sugar content of foods.

A comparison group of 51 experts - researchers, healthcare professionals and policymakers working in obesity, nutrition or physical activity in Ireland and the UK - completed the same survey. This allowed the research team to benchmark public views against expert understanding.

Results

Perceived causes of obesity

The public placed more emphasis on individuals' choices, while experts emphasised environmental and societal causes. Most members of the public recognised at least one environmental cause, for example the widespread availability of unhealthy food. However, they rated individual causes, such as people not making enough effort to exercise or eat healthily, as equally or more important. The public in Ireland were less likely to recognise environmental causes than the public in the UK or US.

Experts instead highlighted environmental factors, including food systems, advertising, portion sizes and neighbourhood design. 

Perceived responsibility

Across all three countries, the public assigned most blame and responsibility for the obesity epidemic to individuals, with far less attributed to businesses or government.
Experts assigned significantly less responsibility to individuals and more to government and businesses, reflecting scientific agreement that the causes of obesity are largely environmental and societal.

Views on obesity as a health problem

Both public and expert samples believed obesity is a major public health issue. The public rated it as serious; experts even more so.

Knowledge of prevalence and consequences

Public understanding of obesity prevalence and related health conditions was reasonably accurate. Participants correctly identified which health outcomes were associated with obesity and tended to slightly overestimate obesity rates.

Policy support

The public favoured policies they thought would be effective and fair, but their perceptions of which policies fitted these criteria did not match those of experts. The public tended to support subsidies or informational campaigns, believing these would be effective at reducing rates of obesity. Experts, by contrast, believed restrictions (such as food regulations limiting levels of fat, salt and sugar in foods) and taxes would be more effective, and were more supportive of these measures.

Members of the public who attributed greater responsibility for obesity to individuals and less to businesses and governments were less likely to support the more interventionist policies like restrictions and taxes.

Conclusions

This study highlights a gap between public and expert perceptions of the obesity epidemic. Although the public believe that obesity is a serious health problem and are aware of many of its consequences, they place far greater emphasis on individual behaviour and much less on environmental and societal causes than experts do. 

These beliefs shape attitudes to policy. To build support for measures that might reduce obesity, public health communications may need to focus less on the seriousness of obesity - a message the public already acknowledges - and more on explaining how environmental and societal factors cause it.

Moreover, moving away from narratives that emphasise individual blame can help to reduce stigma and support public health efforts.