Written evidence for the Health and Social Care Committee on Food and Weight Management
Response authored by: Prof Peter Scarborough, Dr Jessica Renzella, Alice O’Hagan, Margarida Bica, Lia Willis, Nava Gottlieb, Dr Ben Amies-Cull, Dr Hannah Forde
Introduction: We are researchers in the Sustainable Healthy Food Group in the Nuffield Department of Primary Care Health Sciences, University of Oxford. We conduct policy-relevant research on population-level interventions and policies to improve diet in the UK. This includes co-designing interventions and policies with the public, policymakers and the food industry, and evaluating their impact in field trials. In this evidence submission we have responded to questions about food and prevention, mainly focussing on evidence generated by research from our team. Our colleagues (Morris et al) will submit separate evidence on treatment of obesity.
The framing of this question implies that existing public health policies have not reduced obesity rates in the UK. The veracity of that statement depends upon the counterfactual under consideration. Compared with past rates, it is true to say that obesity rates are not reducing (or certainly not reducing in all population groups). But obesity rates today are lower than they would otherwise be in a hypothetical UK without public health policies. In this response, we have interpreted the question to mean ‘why are existing policies relating to food and diet not enough to return rates of obesity back to levels previously seen in the second half of the twentieth century’.
The (food) environment does not prioritise or promote health. We are experiencing an ‘industrial epidemic’ whereby companies produce and market unhealthy foods and beverages that are “hyper-convenient and seductively attractive” (Mialon et al., 2024). This dynamic is fuelled by an emphasis on economic growth and profits above other goals, e.g. health, wellbeing, justice, and sustainability.
(Over)emphasis on individual responsibility. Obesity policies place too much emphasis on individual responsibility which is generally not the most effective or equitable way to tackle obesity and related health issues (Griffin et al., 2012 & Adams et al., 2016). For example, education campaigns and labelling interventions assume that once informed people will make healthier choices. This assumption ignores the complex food environment that promotes unhealthy products and unhealthy consumption behaviours. These policies have an important role to play when implemented alongside interventions that act on the choice environment, but alone are not enough, and may widen health inequities.
Regulation gap. Regulatory action is necessary to reshape the food environment, however, there is a gap between what we know will work to improve diet and obesity outcomes and what the Government regulates. For example, in the Government response to the House of Lords Committee on Food, Diet and Obesity report, the Government conceded that "industry needs to do more" but did not commit to any necessary “decisive regulatory action” (DHSC, January 2025). Lack of regulation, voluntary industry commitments, and watered down regulation, for example, delayed and watered down restrictions on junk food advertising, miss important opportunities to address the commercial determinants of health (the systems, practices, and pathways through which commercial actors drive health and equity (Gilmore et al., 2023)).
Implementation gap. The implementation gap consists of 1) Failure to implement policies and interventions; 2) Failure to develop policies that are readily implementable; 3) Failure to scale and sustain small and short-term projects. Research has shown that many government obesity policies in England have been proposed in a way that does not support implementation (Theis & White, 2021).
Policies/intervention do not adequately address the underlying determinants of obesity. ‘Band-aid’ solutions will not address the root cause of obesity. Research has found that there is insufficient reference to social, cultural and economic issues related to obesity in childhood obesity interventions and even when social determinants of health are addressed, policies and interventions still prioritise individual lifestyle and behavioural interventions (Kriznik et al., 2018 & Medvedyuk et al., 2018).
Evaluation evidence gap. It is difficult to know what works for whom and why if policies are not monitored and evaluated. This is a particular issue for voluntary industry commitments, small-scale or local-level interventions with limited financial resources, and policies and interventions that do not embed evaluation plans into their implementation plans. Limited or lack of evaluation evidence can result in ineffective policies continuing unchecked; missed opportunities for necessary policy adaptations and improvements; and missed opportunities for promoting effective policies. Research based on a comprehensive mapping exercise also suggests that policy evaluations often lack a health equity focus (Blanchard et al., 2024).
Limited co-design with (under-represented) citizens. One size does not fit all. Context is an important determinant of the effectiveness of policies and their implementation. Co-designing interventions with key stakeholders and citizens can support the development of appropriate and effective interventions with better implementation success (Breda et al., 2019 & Greenhalgh et al., 2016). Government efforts to support co-design are encouraging, for example The National Food Strategy for England’s use of co-design to determine its scope and implementation, however, co-design has not been embedded as a standard part of the Government’s obesity policy design process and/or not reported on. Obesity policies that do not reflect the lived experience of the most vulnerable members of society may struggle to gain support and deliver successful results.
What can the Government do differently?
Respond to complexity with more ambitious and systemic solutions. The food system is complex and multifaceted. The Government should focus on:
1) Interventions that address the commercial and social determinants of health.
2) Ambitious and mandatory interventions that focus on holding industry actors accountable.
3) Implementable, scalable, and sustainable policies and interventions.
4) Committing more time and resources to co-designing policies with key stakeholders and citizens.
5) Supporting the generation of evaluation evidence and implementing the learning of that evidence into subsequent strategies.
There is no single policy that will address the obesity epidemic in the UK. Policies need to be put in place that impact on the food system, on individual food environments (e.g. shops, canteens, etc.) and provide support to individuals making decisions in those environments. Where context is important, these policies need to be smart enough to understand local challenges and opportunities and would benefit from co-design with the public and industry stakeholders to find solutions that work in specific settings. Well-conducted evaluations of such interventions can help guide choices towards the most effective interventions available. Our MRC-funded systems mapping research in the London Borough of Newham demonstrated the value of engaging residents in identifying areas for action to create healthier diets (Renzella et al., 2025). Mapping with local residents revealed contextualised determinants of unhealthy diets that may not have otherwise been uncovered if residents were not engaged in this participatory manner. For example, specific local council actions and policies, including not enough health-promoting and resident-minded planning (e.g. limited high street diversity) and advertising (e.g. too much junk food and not enough healthy food advertising) policies. It also demonstrated public support for tackling environmental-level risk factors, specifically related to the junk-food environment. Similarly, our SALIENT project conducted ten trials in different food settings and found that small increases in the healthiness of food purchasing are possible with contextualised changes in the choice architecture – all of which will be important to help improve the health of the nation. They will be supported by the Government aim to monitor healthiness of food sales and to set mandatory targets for businesses, but the success of this policy will depend upon the metrics used and the proposed timeframe for implementing targets should be brought forward.
But choice architecture interventions will only go so far, and for transformative change they need to be accompanied by mandatory policies that affect the food system. The most recent successful example of such a policy is the Soft Drinks Industry Levy. There are many calls for extension of the SDIL to taxes on unhealthy foods, including in the recent National Food Strategy. Our co-design work with the public (NIHR-funded COPPER project) used deliberative forums with members of the UK public to understand preferences for food subsidy and tax policy scenarios that could promote healthier and more sustainable food choices, as well as the reasons for these preferences (Forde et al., in press). The results suggest that members of the UK public would support new taxes on unhealthy foods to create a fairer, healthier, and more sustainable food system, but they should be accompanied by subsidies for healthier foods (e.g. fruit and vegetables). Such fiscal policies, if aimed at rebalancing the food budgets of the UK population towards healthier diets, could have a far larger impact on obesity than choice architecture interventions.
Government-led obesity policies, both in England and worldwide, have adopted a wide range of strategies for tackling obesity and reducing the consumption of less healthy foods. These interventions have largely centred on high-agency strategies that require significant individual-level thought and effort (Adams et al., 2016). Examples of these include the Healthier Families, previously Change4Life, programme in England, and labelling interventions, such as calorie labelling in the out-of-home sector introduced in 2022 and front-of-pack (FOP) traffic light labelling. These require the population to notice and understand the information provided and have the capability, opportunity and motivation to change behaviour (COM-B model) (Michie, Van Stralen and West, 2011). But the UK has previously been pioneering in its implementation of low agency interventions, for example, being the first territory worldwide to introduce statutory scheduling restrictions of food advertisements to children. England also implemented the reduction and reformulation voluntary programme in 2016. Other examples include taxation, such as the sugary drinks levy implemented in the UK in 2018, encouraging manufacturers to reduce portion sizes and sugar in soft drinks, which has been associated with reductions in sugar levels in drinks, increases in price of high sugar drinks, falls in purchases and consumption of soft drinks, and falls in dental caries and obesity rates in children (Rogers et al., 2023; Luick et al., 2024).
There are some examples of cohesive, co-ordinated approaches incorporating multiple interventions that have been tried internationally. For example, Chile implemented a food labelling and marketing law in 2016, consisting of a multiphase set of policies including mandatory warning labels, restricted food marketing to children and banning sales of unhealthy foods (nutrients of concern) in schools. Evaluations using interrupted time series analyses (Taillie et al., 2024) and cross-sectional designs (Rebolledo et al., 2025) have shown sustained decreases in the proportion of food and drinks high in nutrients of concern, with stricter regulatory limits associated with decreases in these nutrients over time, highlighting the effectiveness of a comprehensive cohesive approach.
2.1 Where should the balance lie between voluntary and mandatory policies, and between tax and incentive?
Recent evidence syntheses suggest that voluntary policies are insufficient at encouraging healthier diets, and whilst fewer countries have implemented mandatory policies, there is evidence for their effectiveness in improving dietary intake (Blanchard et al., 2024; Boyland et al., 2022; Gressier et al., 2025). Evidence submitted by researchers from the Nuffield Department of Primary Care Health Sciences in a previous parliamentary inquiry highlights the comparative effectiveness of voluntary versus mandatory policy within the UK, with over 30% of soft drinks reducing their sugar content between 2016 and 2018, attributable to the Soft Drinks Industry Levy, whilst foods only saw a 5% reduction over the same time period, under the voluntary sugar reduction targets (Bandy et al., 2020; Bandy et al., 2021; Scarborough et al., 2020).
Health modelling work conducted by Amies-Cull et al. (2019) indicates that realising the full potential health benefits of the UK’s voluntary sugar reduction programme is reliant on the policy being adhered to completely and operating through all intended mechanisms. Bandy et al. (2021) found that out of the top-selling 50 companies across five food categories that contribute the most to sugar intake in the UK, just under half (24) met the interim 5% sugar reduction targets in 2018. Similarly, in the out-of-home food sector, 43% of menu items offered by the 21 highest-grossing restaurant chains in the UK were found to meet all of the targets they were eligible for across the sugar, salt, and calorie reduction targets, in 2024 (O’Hagan et al., 2024). Together, this evidence suggests that there is a lack of engagement across the food sector with the current voluntary policies, which could be limiting their effectiveness in improving diet quality.
Types of interventions more likely to reduce inequalities: There are a few important principles relevant to addressing inequalities in obesity. Population-level interventions are broadly more likely to require less individual agency (Adams et al., 2016) so impact a wider range and number of people, though their effect on any one individual may be small. They are more likely to impact groups that are harder to reach, so may better reduce inequalities than individual-level approaches.
Addressing deprivation and the social determinants of health: It is not a coincidence that obesity is socially patterned with deprivation: to address obesity-related health inequalities requires addressing their underlying socioeconomic inequalities. Income, deprivation and ethnicity predict obesity rates (Amies-Cull et al., 2022). Micro-level human decision-making and macro-level social determinants converge in more deprived communities to increase obesity. These causes form a “complex adaptive system” whereby changing one factor alone has limited impact (Rutter, 2012). As argued above, it is possible to change this complex adaptive system with structural-level policies, and with policies aimed at changing the choice architecture that have been co-designed with the public and food industry to ensure they are appropriate for the context.
Exposure to takeaway outlets is socially patterned and may fuel social and ethnic disparities in obesity: Research has shown that takeaway foods, notably fast-food, are often highly calorie-dense, consumption of fast-food tends to lead to weight gain and exposure to fast food outlets may be associated with obesity (Burgoine et al., 2014; Burgoine et al., 2018; Burgoine et al., 2021). Of particular concern is the combined exposure to takeaway outlets at work, home and whilst commuting. This was found to be correlated with obesity (Burgoine et al., 2014). A 2024 study predicting menu healthiness of all physical out-of-home food outlets drew attention to the ‘double burden’ experienced by more deprived communities in England of having more outlets, and also less healthy options (Huang et al., 2024).
Enforcing and monitoring planning policies to curtail the opening of new unhealthy food outlets is needed for addressing inequalities in obesity rates: Modelling has predicted that a 50% reduction in growth of new takeaways near schools in 6 local authorities in England could reduce obesity rates by 1.5 to 2.3 percentage points by 2031 in adults aged 25-64 (Rogers et al., 2024). In Gateshead, three planning policies were implemented: 1) exclusion zones around schools; 2) limiting outlet density at a cap; and 3) refusing planning permission in areas above a child obesity rate threshold. When compared with controls, the following results were reported: a reduction in the density and proportion of fast-food outlets (Brown et al., 2022) and a reduction in the prevalence of overweight and obesity in year 6 children in the deprivation quintile with the highest concentration of outlets before the intervention (Xiang et al., 2024).
Need for specific, ambitious actions: We support the intention to set a consistent vision that appreciates the breadth and complexity of the food system, and look forward to the announcement of policy areas and strategies through which the Food Strategy intends to meet its vision and outcomes, and the precise metrics and indicators that these will be measured by. Though the Strategy has mapped existing interventions, these alone are insufficient to realise the ambitions of the Food Strategy – further, ambitious interventions are required.
We also support the announcement in the NHS 10 year plan of monitoring and targets for sales of unhealthy foods, although note that a) the policy will only be successful if appropriate metrics are used for monitoring, and b) the timeframe for implementing targets (which are necessary for prompting change in behaviour) is not too distant. In principle this policy could provoke widespread adoption of smart, contextualised choice architecture interventions that could have a real impact on health outcomes. We encourage greater emphasis on publishing the results of robust field trials of choice architecture interventions to support the uptake of these interventions.
Choice architecture interventions, however, will not be transformative without mandatory policies that are structural and address the obesogenic food system. Our work in the COPPER project (Forde et al., in press) has demonstrated public support for policies that aim to make healthier diets more affordable for all. Cleverly designed taxes and subsidies in the food system can push consumers away from unhealthy foods and towards healthier products. If well-designed, these policies need not drive up the cost of food, resulting in the same tax revenues as are currently received from food and drink but redistributed so that unhealthy food categories receive higher rates and healthier food categories are subsidised.
Enforce greater data transparency: We support the Food Strategy’s intention for a joined-up approach to use of data. The Food Data Transparency Partnership (FDTP) has not fulfilled its full potential as it currently expects food companies to voluntarily report health data. This encourages selective reporting by only those performing well, and at its worst, gives a skewed picture of performance and progress in the food system. The absence of transparent data has direct consequences on our ability to monitor the healthiness of food companies’ offerings and evaluate the effectiveness of food policies and interventions.
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