Sustainable Diets and closing the intention–behaviour gap


by Kate Platts and Cecile Morris

Diets inextricably link human health and environmental sustainability. Evidence suggests that diets that place the least burden on the planet’s natural resources are also those which have the greatest benefit for human health. Beef cattle and dairy farming globally has a demonstrable detrimental impact on the environment, and finding ways to mitigate environmental risks through modified food consumption has become a key area of study.

In this blog, we discuss the ‘Planetary Health Diet’ launched in early 2019 and introduce our on-going research in the area of consumer attitudes towards sustainable diets. We examine the controversial response from the agricultural and nutrition sectors as well as the media. We also explore UK consumer behaviour in relation to meat and dairy consumption, touching on drivers of meat consumption and barriers to dietary change but also recent market trends. Thinking about the plethora of mainstream media articles reporting on climate change and the need to act now, we ask ourselves: What support is available to those who want to adopt a ‘greener’ diet? What resources would help those struggling to make dietary changes and effectively close the intention-behaviour gap?

If you feel this is of relevance to you, read on!

What do we know so far?

The impact of food systems on the environment

The production of food for human consumption has a significant impact on the environment in which it is produced and on the planet as a whole. It is likely to be the single biggest cause of global environmental change today, with an estimated 20-30% of all anthropogenic greenhouse gas (GHG) emissions emanating from global food systems. However, not all agricultural food systems are created equal. The environmental impact of cattle rearing and farming are by far the biggest contributors to methane (CH4) and nitrous oxide (N2O) emissions – the most potent and damaging to the earth’s atmosphere. Efforts to increase food chain efficiency can help mitigate the problem but reducing consumption of GHG-intensive foods, while also meeting health goals, is now seen as key. In this, food consumers have a leading role to play in influencing food production and consumption practices, especially in developed countries where food is abundantly available.

Sustainable diets

The term ‘sustainable diet’ has been coined to describe diets with ‘low environmental impacts which contribute to food and nutrition security and to healthy life for present and future generations’, thus signalling an inextricable link between environmental sustainability and human health. While food system-related climate change is undoubtedly a great threat to the planet, the fact remains that 821 million people around the world are undernourished, with 770 million experiencing severe food and nutrition insecurity. Worldwide, the picture is one of gross inequalities with meat and dairy consumption disproportionately concentrated in westernised, developed countries. In this respect, sustainable diets become particularly complex when geographical, social and cultural contexts are considered, and healthy diets do not always necessarily equal environmentally sustainable ones. Finding simple solutions to these deeply complex issues is challenging. Nevertheless, attempts have been made to define global diets that are both ‘healthy’ and ‘sustainable’. The ‘Planetary Health Diet’ proposed by the EAT-Lancet Commission in 2019, attempts to synthesise and distil the research of 37 leading scientists from various disciplines, including human health, agriculture, political sciences and environmental sustainability, into simple food-based dietary guidelines for the global population. It is the first report of its kind to attempt to set universal scientific targets. It recommended a major dietary shift towards fruits, vegetables and legumes and away from meat and dairy consumption, which its authors assert will ease pressure on natural systems and avert 10-11 million deaths per year from non-communicable diseases. However, recognising the burden of hunger and undernutrition in many low- and middle-income countries, the Planetary Health Diet focuses primarily on reducing excessive meat consumption in wealthier continents such as Europe, North America and Australia.

The response to the Planetary Health Diet

The Planetary Health Diet has not been universally endorsed. The Sustainable Food Trust said the report fell short due to ‘a fundamental lack of agricultural understanding’ with some of the main dietary recommendations being ‘incompatible with the food production outcomes of truly sustainable farming systems’.  The Agriculture & Horticulture Development Board UK said that ‘farming, in particular dairy and red meat…makes best use of naturally occurring assets to feed a growing population’, and that red meat and dairy products are ‘an important nutritional part of a healthy, balanced diet.’ Nevertheless, many applauded its publication and a report by the UK Food, Farming & Countryside Commission recommended moving to a more plant-based diet, encouraging people to ‘buy healthy’ and empowering communities to shape and drive their local food systems in a sustainable way. Despite the mixed reviews that the EAT-Lancet Commission report and its proposed Planetary Health Diet have received in mainstream media, the coverage (BBC, 2019a; BBC 2019b; CNN, 2019; Guardian, 2019; New York Times, 2019) will have raised public awareness of the issue. While it seems unlikely that British consumers will adopt, en masse, a vastly meat- and dairy-reduced diet, the tide does appear to be turning towards different dietary patterns in a nation of increasingly conscientious consumers.

Consumer behaviour in the UK

The relationship between dietary choice and climate change may not be obvious, and scepticism about the link between climate change and dietary choice is widespread. Nevertheless, there appears to be a groundswell of support for reducing of meat and dairy intake amongst the British general public. According to a 2019 YouGov poll, while the vast majority of British consumers (73%) eat meat, 14% report that they are following a ‘flexitarian’ diet, which can be described as semi-vegetarian with only the occasional inclusion of meat or fish. Furthermore, 69% of flexitarians and 26% of meat-eaters who do not currently identify as flexitarians report that they’d like to cut down on the amount of meat they eat. Some research suggests that environmental concerns are generally ranked lowest behind animal welfare and health amongst people considering the benefits of a plant-based diet. However, around 83% of UK adults claim to have recently bought food or drinks with ethical certifications, with 38% citing environmental concerns as the primary reason for doing so.

Retail data too show that consumer purchasing habits in the UK are changing, and that meat and dairy substitutes are increasingly popular amongst both vegetarians and active meat-reducers, perceived as both healthy and easy to prepare by adopters. This is something that Quorn, the market-leader in the meat-substitute market, has capitalised on with a new ‘healthy protein, healthy planet’ campaign in 2019, targeting consumers who care about both the health and sustainability agendas. Provision of dairy-reduction information and campaign messages in the UK come predominantly from not-for-profit groups such as Veganuary and the Vegan Society. Campaigns such as ‘Plate up for the Planet – eat to save the world’ position themselves as campaigns for sustainable diets with a strong focus on environmental issues and animal welfare. However, we lack research on how peoples’ intentions and actual behaviours are influenced as a result.

Barriers to closing the intention-behaviour gap for dietary change

There appears to be growing acceptability and accessibility for meat- and dairy-reduced products. Yet, significant barriers exist, even for those motivated to move towards a more sustainable diet. Closing the intention-behaviour gap for dietary change—which is central to individual and planetary health—requires a better understanding of the socio-cultural contexts of individuals’ dietary behaviours. Meat attachment is deeply entrenched in western societies, driven by the historical, social and cultural importance of eating meat. Far from being a result of purely rational decision-making, human behaviour is the result of an intricate interplay between habits, automatic responses to the environment, conscious choice and calculation, and the influence of complex social and cultural values. Thus, an individual may fully intend to reduce meat and dairy consumption yet find themselves unable or unwilling in practice to make the necessary changes.

As such, closing the intention-behaviour gap doesn’t just require a better understanding of intentions and behaviours; it requires better forms of support to enable people to enact dietary changes that support sustainability. Unlike with other positive behaviour changes, there is currently no easily accessible support mechanism for people wishing to reduce meat and dairy intake. This is where our research comes in. We are currently working to identify factors that can influence the reduction of meat and dairy intake, and the mechanisms that would best support individuals and empower them to effect sustainable dietary changes. 

How you can help

We are carrying out research on sustainable diets, and you can get involved. We have developed a baseline survey to try and model attitudes and behaviours towards sustainable diets based on elements of the Theory of Planned Behaviour as well as the Self-Determination Theory. Beyond this, we are also piloting small scale interventions aiming to support behaviour change in people who wish to reduce their meat and dairy intake. The data acquisition part of this project will be live until August 2020. You can get involved by filling in our survey or contacting the principal investigator: Dr Cecile Morris ( 

About the authors:

This blog is based on MSc research (‘Sustainable Diets: Closing the Intention—Behaviour Gap’) by Ms Kate Platts (, under the supervision of Dr Cecile Morris ( in the Department of Service Sector Management, Sheffield Business School of Sheffield Hallam University.

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