The shift to sustainable diets

Richard Carmichael works on behaviour change, public engagement and policy for Net Zero. He tells us how food policy can help us reach climate goals.

16 November 2020

As the climate, environmental and public health crises continue to worsen, there is a clear and urgent need for policy to support wider and faster shifts towards sustainable diets. After many years of neglect by policy, the context in the UK now shows signs of being more favourable for such intervention, due to the legally-binding Net Zero target of summer 2019, the growth in plant-based eating, and the opportunity Brexit presents to reform agriculture.

The social and cultural aspects of eating practices ensure that changing them remains a challenge. But well-designed interventions could make these aspects begin to work in favour of change. There are a number of low-risk, low-cost pragmatic steps that can and should be taken to reduce emissions due to diet. These could also deliver considerable co-benefits for health.

As part of renewed interest in the contribution of behaviour change to meeting climate commitments, the Committee on Climate Change appointed me to set out policy recommendations to support such behavioural and societal shifts for Net Zero. The resulting report, Behaviour change, public engagement and Net Zero, released in October 2019, covered how government policy could better support public engagement with climate action generally and how to support behavioural and societal shifts to reducing emissions in four areas: driving, flying, what we eat, and how we heat our homes. To a large degree this will be through lowering barriers to low carbon choices, and here I will focus on the psychological aspects of behaviour change relating to food.

Putting it on the menu
One such barrier is the lack of plant-based options on catering menus. In the UK, 30 per cent of all meals are provided through education, healthcare and other government funded institutions. But they do not routinely offer any purely plant-based options.

Broadening choice rather than introducing restrictions is an obvious first step in enabling people to shift to lower-impact and healthier eating habits. A series of experiments at Cambridge University Catering Services has generated evidence on the effectiveness of encouraging plant-based diets without restricting consumer choice. These showed that doubling the availability of vegetarian dishes increased vegetarian sales by 42-97 per cent, especially among meat eaters. This was achieved without banning or removing meat from menus. New regulation should require that all schools, hospitals and other public sector catering outlets include at least one fully plant-based menu option that is available for everyone every day without special request (as suggested by the Catering For Everyone campaign). This has already been enacted into law in Portugal. This would not only cater to those already willing but unable to access plant-based meals but would introduce omnivores, and the growing number of flexitarians, to readily-available, healthy, plant-based dishes with potential for spillover into their eating habits beyond the school or hospital and for social influence effects to ripple out to wider social circles.

Improving access to plant-based foods is consistent with Richard Thaler’s maxim that ‘If you want people to do something, make it easy’. Dietary change also involves the widespread adoption of new behaviours and products, so a Diffusion of Innovation perspective is also valuable. Innovations – products, technologies, behaviours or ideas – tend to be more rapidly adopted when they can be trialled and when adoption by others is visible. Getting plant-based foods on the menu will increase both their trialability and give plant-based eating more visibility.

Social barriers and social identities
Lowering the material barriers to eating plant-based foods through menu changes does not just make it easier to get hold of vegan foods – it also reduces social barriers to choosing plant-based food. Firstly, those seeking plant-based foods can eat with friends and colleagues rather than having to go elsewhere. The visibility or observability of others’ food choices is particularly valuable and relevant for plant-based eating due to the social and cultural associations around meat eating and meat avoidance.

The foods we choose can affect how we are seen by others and how we see ourselves. Twenty years ago I carried out doctoral research at Loughborough University Social Sciences on the social psychological aspects of vegetarian and vegan identities. The diary and interview case material from new and aspiring vegetarians and vegans showed that cultural ambivalence around meat and meat rejection played out in their account-giving and self-narratives.

Giving an account of themselves as vegetarian or vegan involved managing various dilemmas and avoiding stereotypes. There was a dilemma of moral superiority: how to talk about their motivation for vegetarianism/veganism without criticising others and being seen as a preacher or killjoy. And there was a dilemma of abstinence: how to present the self as consistent yet also ‘human’ rather than boring, abstemious and monk-like. As one diarist reported, ‘Something they said did bother me though...  they said, “You think you’re above us, don’t you, but you’re a bit boring really, aren’t you?”’ These social and rhetorical aspects can make being vegetarian or vegan a more challenging choice of lifestyle and identity. Often, managing these dilemmas of identity involved vegans presenting themselves as ambivalent, conflicted and divided. Another commonly-reported strategy was to avoid the topic altogether, as ‘there’s no nice way to talk about it really… you’re always going to have a hard time’.

Talking about diets and dietary change can be helpful. Social networks can help vegetarians/vegans through information, emotional support and reinforcement of group norms. Coaching conversations can also be powerful for getting ‘unstuck’, clarifying and moving towards goals, or increasing resilience. These days, there is greater focus on the environmental and health benefits of plant-based eating than 20 years ago, but talking about veganism and meat eating can still draw attention to social identities and differences in ways that are uncomfortable and unhelpful. Rather than just talking about it, or changing the subject, the most promising strategy for normalising vegan foods will be to change the material and rhetorical context to be more vegan-friendly.

When enjoyable plant-based food is readily available, eating vegan becomes easy and unremarkable rather than strict, extreme and boring. Less justification is expected. The line between vegans and non-vegans becomes less divisive and vegan stereotypes lose a lot of their potency. It becomes less ‘other’ and more normal.

Meat analogues and blended products
A second strategy for making sustainable plant-based eating easier is afforded by plant-based meat substitutes or ‘analogues’ which typically have around one tenth the greenhouse gas (GHG) footprint of meat. Plant-based meat and dairy replacements have an important role to play in shifting to sustainable diets as they reduce the complexity of plant-based eating and are highly compatible with existing habits (both associated with rapid innovation adoption).

Meat analogues or substitutes, by definition and design, fit in with existing habits – a plant-based burger is still a burger, not a deep-fried insect or a meal replacement drink. Analogues also have clear advantages over meat for health (less saturated fat), environment, and animal welfare – all now common concerns. Costs should reduce substantially as plant-based alternative proteins and meat and dairy replacements increase their scale of production and follow the usual ‘learning curves’ for new technologies. Another food technology route for reducing meat intake is offered by products which blend animal products with plant ingredients. Blended products are already showing success in the USA with the ‘Blended Burger’, which incorporates 30 per cent mushroom into minced beef.

As with broadening menus, the perception that a plant-based diet is extreme, weird or ‘other’ will diminish as analogues continue to improve in taste, texture and price. In light of their value to meeting climate goals and reducing public health costs, government should accelerate the further development of meat and dairy analogues through seed-funding research and commercialisation of new products with a focus on consumer appeal, nutrition and sustainability.

Labelling and personalised feedback
Improving the availability of tasty, healthy and affordable plant-based options will lower several barriers to shifting diets. A second major bottleneck to change centres around more informed consumer choices.

Reducing UK consumption of high GHG-impact meat and dairy, which tend to be high in fat, is highly consistent with a reduction in calories and saturated fats. There is an opportunity for greater awareness about the nutritional and environmental impact of foods to work together to produce behaviour change.

While consumers can find nutritional information in numerical form confusing, there is evidence that graphical ‘traffic light’ nutrition labelling (which indicate green, amber and red ratings for calories, fat, saturates, sugars and salt content) helps consumers make informed decisions about the food they are purchasing. Traffic light labelling is currently voluntary but there is demand among UK consumers (who are the most overweight in Western Europe) for clearer information. Brexit presents an opportunity to improve the currently confusing, and at times misleading, front-of-package (FOP) labelling and make standardised graphical nutrition labelling mandatory.

But even more interesting and potentially effective for behavioural change is that mandatory labelling would allow personalised feedback. Consistent and mandatory traffic light labelling opens up the possibility for shoppers to receive feedback about their food purchases as a whole. This feedback would also take into account different product/package sizes. Such aggregating and weighting of food label data is difficult for a human to perform but easy for technology. Consumers would have a clear, highly visible picture of their overall shopping and eating patterns, which are otherwise difficult to see. Over time, this could encourage shoppers to take more notice of individual product labels. Survey research has demonstrated strong consumer interest in having this kind of whole basket nutrition feedback printed on till receipts, indicating its potential for informing healthier food purchases. Smartphone apps and shopping websites could also deliver this feedback for a customer’s weekly shop, tracking it over a longer timeframe.

Importantly, this would also give consumers feedback on progress made towards improving their purchasing habits (or alert them if they drift into less healthy patterns of shopping). Goal setting, tracking, monitoring and feedback are commonly used strategies in digital behaviour change interventions, which motivate partly through making goal setting and progress more specific and measurable.

Getting specific about producers
This kind of personalised feedback on overall purchasing habits could also be offered for the environmental impact of a household’s food shopping. Surveys suggest that 72 per cent of UK shoppers want information on the climate impacts of their foods to help them make more informed choices. Feedback could also benchmark a household’s shopping patterns against guidelines for sustainable diets.

Environmental impact labelling of food has a further pay-off when it is based on producer-specific data. High-impact beef producers can emit 12 times more GHGs than low producers and have nearly 50 times the land use of low-emitting beef producers. Halving consumption of animal products and avoiding the highest-impact producers would achieve 73 per cent of the GHG emissions reduction potential of switching to completely plant-based diets. Significant emissions reductions could be achieved therefore by consumers making easy choices of lower-impact producers/brands of the same food type. The Danish government has recently indicated its commitment to climate food labelling and feasibility has already be demonstrated with free-to-use software (e.g., CoolFarmTool).

Under the Common Agricultural Policy, about three-quarters (€29-33 billion) of direct payments to EU farmers go to producers of livestock or livestock fodder – almost a fifth of the EU’s total annual budget. The producer-specific data used for food environmental impact labelling could also be used as the basis for administering a revised system of financial support that rewards lower-emission food producers to incentivise changes in production methods and product development and filter-down as price signals to consumers.

Policy strategies: box text

  • Ensure one fully plant-based option on all public sector catering menus available to everyone everyday
  • Introduce standardised 'traffic light' labels on food showing climate impact and nutrition
  • Enable consumers to share their purchasing data with third parties offering feedback on overall shopping habits
  • Revise agricultural subsidies to incentivise lower-emission food production and consumption

More than talk
Together these recommendations for policy comprise a two-step approach to reducing diet-related emissions. Solutions will need to be introduced in a coordinated sequence to maximise impact and public acceptance. The first step is to improve consumer choice and availability of data, and the second is to introduce financial incentives for change in production and consumption.

Across all areas of behaviour change for Net Zero, it will be vital to lower existing barriers to making low carbon choices easy, attractive, affordable and normal. Where social identities and stereotypes around eating are concerned, barriers create additional social barriers reinforcing the status quo. More than just talk will be needed if everyday life is to support rather than resist the shift in diets that is required. The last couple of years have been interesting times for veganism in the UK. With help from well-designed policy, things could get a whole lot more interesting in the coming years.

- Dr Richard Carmichael is a Chartered Psychologist and a Research Associate in the Centre for Environmental Policy, Imperial College London. [email protected]

Key sources
Carmichael, R. (2002). Becoming vegetarian and vegan: Rhetoric, ambivalence and repression in self-narrative. Doctoral thesis, Loughborough University. Available at
Carmichael, R. (2019). Behaviour change, public engagement and Net Zero. A report for the Committee on Climate Change. Available at  
Committee on Climate Change (CCC). (2019). Net Zero: The UK’s contribution to stopping global warming. London. Retrieved from