The affordability of healthy food is a key barrier to maintaining a healthy weight. This challenge has only intensified due to rising living costs and higher-than-average inflation over the past four years.

While 11% of the UK population are officially classified as “food insecure” – having a risk of, or lack of access to, sufficient, varied food – a much larger proportion of people struggle to afford a healthy diet. This contributes to the fact that two-thirds of adults in the UK are affected by overweight or obesity.

Targeted interventions to tackle food insecurity like food banks, free school meals and the Healthy Start voucher scheme are a vital lifeline for many and play a crucial role in supporting people on low incomes to access the food that they need. However, they only reach a small fraction of the population. These solutions should be prioritised for those on the lowest incomes, but as we've seen in the face of growing food costs, the affordability of a healthy diet is becoming an issue for more people. Therefore, if making healthy food more affordable is to be a solution for tackling excess weight at scale, we need new strategies that benefit a wider part of the population.

Estimates of how many people struggle to afford a healthy diet vary widely. The Food Foundation’s 2018 analysis found that 47% of UK households do not spend enough on food to meet the UK government's healthy eating guidelines, known as the Eatwell Guide, which sets out the proportion of fruit and vegetables, carbohydrates, protein, dairy and fats recommended for a healthy diet. 

In contrast, the World Bank’s Food Prices for Nutrition places the percentage of the UK population that cannot afford a healthy diet at just 2.5% for 2022. Surveys capturing personal experiences suggest a figure somewhere between these extremes. Much of this variation depends on how a "healthy diet" is defined – or in some cases, not defined at all.

While the most recent work by the Food Foundation does not provide updated figures on the proportion of households spending enough to meet the Eatwell Guide, it shows that the cost of eating the diet recommended by the Eatwell Guide diet has risen from £5.99 per adult per day in 2018 to £9.00 in 2025. This increase is considerably higher than the change in average food expenditure over a similar period. As a result, it is likely that even fewer households can now afford to follow the UK government’s healthy eating guidelines than the 47% estimated in 2018. The Food Foundation’s approach prioritises a healthy, balanced and environmentally sustainable diet, basing affordability estimates on full adherence to the government’s Eatwell Guide recommendations.

While following these guidelines will likely bring significant health benefits, doing so is not necessary to avoid excess weight; less than 0.1% of the population comply with all nine Eatwell recommendations, considerably fewer than the 34% able to maintain a healthy weight. This suggests that while the Eatwell Guide is an important benchmark for overall health, it may not be the most practical measure for assessing how affordability affects obesity. It is possible that setting such a high bar for a healthy but affordable diet risks making the issue seem insurmountable to policymakers and industry, resulting in policy paralysis as the issue is deprioritised. 

At the other extreme, the World Bank’s Food Prices for Nutrition estimate prioritises affordability above all else, using the cheapest items in each food group to meet nutritional requirements – like lentils rather than meat for protein. While important, the price of ingredients is not the only driver of food purchase decisions. The World Bank’s approach largely ignores other important factors such as taste and cultural preferences, alongside time, skills and equipment constraints, which make such a diet impractical and unappealing for many people. In a world dominated by cheap, unhealthy – but also often tasty – options, metrics and policies which do not take into account factors beyond price risk missing the mark.

A realistic yet ambitious goal for an affordable diet to tackle excess weight lies between these two extremes. While the Eatwell Guide remains an important benchmark for overall health, Nesta’s modelling shows that halving obesity prevalence could be achieved through modest dietary changes – specifically, an 8.5% reduction in daily energy intake, or 216 kcal per day (the equivalent of a 500ml bottle of Coca-Cola), for those with excess weight. Crucially, this means that a goal to reduce excess weight across the population  is possible through small, sustained dietary changes across a large number of people, which may be more feasible than making dramatic changes for a few.

Affordability isn’t just about food prices – it’s also shaped by individuals' incomes, alongside the cost of other essentials. While we often think of budgets as fixed "pots", eg, for food, housing, or leisure, the reality is that beyond certain fixed costs like rent, most spending is flexible. This means that lowering absolute food prices won’t necessarily lead to a proportional increase in the purchase of healthier foods, as savings may be redirected elsewhere. 

Over the last 35 years, food prices have generally decreased relative to other goods and services, yet UK obesity rates have doubled. While the recent cost-of-living crisis led to significant food price hikes, prices had been trending downward in real terms before this period. This suggests that the price of food is not the only driver of the choices people are able to make about the foods they buy. We know affordability remains an issue even as the price of food has trended downwards, which indicates that other costs people face – energy, housing, or other essential costs – remain a barrier to being able to afford healthier food. It also indicates that a more feasible and effective way to encourage healthier food purchases, rather than trying to reduce food prices across the board, may be to focus on the relative pricing of healthy vs. less healthy foods. 

Although there is some debate regarding the best metric to use when comparing costs, the most commonly used metric – cost per calorie – shows that healthier food and drink is generally more expensive than less healthy options. Since food choices are influenced by relative prices, narrowing this gap could encourage healthier purchases. However, current strategies to promote healthier eating at scale by addressing the affordability gap often focus on taxing a narrow range of the least healthy products (eg, sugary drinks) or subsidising a limited selection of the healthiest options (eg, fruit and vegetables). This focus on a relatively small number of the healthiest and least healthy items may limit their overall impact on reducing obesity.

The UK’s Soft Drinks Industry Levy (SDIL), a tax on the production and importation of high-sugar drinks, has successfully reduced sugar consumption in adults' and children's diets. This has primarily been through encouraging industry to reformulate their drinks to contain less sugar, but also by encouraging consumers to switch towards cheaper lower or no-sugar alternatives. However, when excluding fruit juice and milk-based drinks which are exempt from the SDIL, soft drinks make up a relatively small portion of the calories (0.6%) in our diets. 

Nesta’s modelling suggests that expanding the SDIL to also cover sweetened milk-based drinks could achieve moderate gains of an estimated 0.6% relative reduction in obesity rates. However, interventions like broader taxes which target a wider range of products, such as a £3 per kilogram tax on sugar and a £6 per kilogram tax on salt for use in processed foods or restaurants (as recommended by the National Food Strategy), have the potential for a significantly higher impact on obesity rates, with Nesta’s modeling suggesting that such taxes could deliver a 12% reduction in obesity rates.

Meanwhile, the NHS Healthy Start scheme provides vouchers to pregnant women and families with young children living on low-incomes to subsidise fresh vegetables, milk, and vitamins. While the scheme offers valuable support to families facing food insecurity, it is not designed or optimised to prevent obesity. Like other subsidy programmes that focus on a narrow range of foods, Healthy Start increases sales of targeted items, but without a corresponding reduction in less healthy options. This leads to a net increase in energy consumption, making this and similar programmes unlikely to reduce obesity rates.

Achieving the small, sustained daily energy reduction  needed to decrease excess weight across the population will require interventions that go beyond promoting only the healthiest options (eg, fruits and vegetables) or discouraging the least healthy (eg, sugary drinks). Encouraging people to shift towards slightly healthier versions of products they already eat – such as swapping regular crisps for baked crisps or chocolate cereal for porridge – offers a more realistic approach than expecting drastic dietary changes like swapping crisps for carrot sticks.

Moreover, these small, more interchangeable swaps may be more likely to replace less healthy options rather than being added to shopping baskets as extras, making them less likely to increase overall calorie consumption. Part of Nesta’s ongoing work, which analyses food and drink purchasing data, aims to identify what a diet that achieves modest energy reduction could look like within preferences and different cost parameters.

Interventions to encourage healthier swaps through relative pricing would need to apply across a wide range of products to achieve meaningful reductions to people’s energy consumption. Offering subsidies on a large number of specific items within food categories through a voucher system like Healthy Start would be complex and potentially unfeasible. 

Nesta’s ongoing work is exploring opportunities to collaborate with retailers on commercially viable interventions that would effectively drive these healthier shifts. What's more, it is clear that in order to maximise their impact on obesity reduction, interventions to make food more affordable should be delivered in combination with other policies that encourage healthier purchases, for example through increased availability, advertising, marketing and promotions.

To achieve our mission to halve obesity by 2030, we need bold, scalable solutions that make healthier food more affordable for a wide range of people. At Nesta, we’re exploring policies and interventions to support healthier eating among those who face financial barriers. As an innovation partner, we aim to collaborate with governments and businesses to test the public acceptability, commercial viability, and impact of these approaches on obesity reduction. 

Leveraging our expertise in behavioural science and design, we will explore how taxes, subsidies, and retail promotions could be optimally designed to maximise health benefits without creating financial challenges for vulnerable groups. We also see opportunities to develop innovative business and funding models that can shift markets and create sustainable pathways for affordable, healthy food.

If you are interested in talking to us about this, please get in touch with Jonathan Bone.