Fighting human-caused climate change over centuries of greenhouse gas emissions to the atmosphere is considered one of the great civilizational struggles of our time.
The impacts of this planetary crisis are already widely known: emissions heat the planet, disrupting the systems and mechanisms on which Earth’s stability depends. And this stability also underpins human societies, and the effects of the disruption are felt with increasing force: droughts, floods, fires and storms tend to be more frequent, intense and lasting, affecting societies as a whole.
In 2015, aware that the situation would worsen if nothing were done, countries around the world adopted the 2030 Agenda for Sustainable Development. The shift in dietary habits is one of the major axes of this global strategy, crossing several of the 17 goals.
Among the main changes are the reduction in the production and consumption of animal-derived products (such as meat and dairy), generally associated with high carbon footprints, replacing them with plant-based products, typically linked to lower environmental impacts.
Additionally, the preference for more local products and those produced under sustainable practices, avoiding packaging and opting for bulk purchases and reducing waste are all changes regarded as fundamental to align eating with the urgency of planetary crises.
Many people today say they are concerned about climate change and many others already have more sustainable diets, whether for health reasons or for concerns about the planet, or both. But is there a direct link between the notion we have of the problem and what we actually change in practice to solve it?
A study on “Sustainable Eating Practices in the Era of Climate Change,” promoted by the Social Observatory of the La Caixa Foundation and developed by researchers from the ISPA – Instituto Superior de Psicologia Aplicada and the European University, shows that the Portuguese (a sample of 3,132 adults) are increasingly aware of the benefits of a healthy diet. However, it reveals that there can be a wide gap between knowledge and action.
In an interview with ‘Green Savers’, Filipa Pimenta and Marta Uva, researchers at the William James Center for Research (which brings together ISPA and the University of Aveiro) help to understand the main results of the study and to perceive what they may mean for the sustainability efforts that are needed to protect the planet, ecosystems and people.
We have a Portuguese population aware of the urgency of fighting climate change and also concerned about the effects on their own health and safety. However, your study shows that this awareness and concern do not necessarily correspond to concrete behaviors, such as changing eating habits, for example. In your view, and considering the results of this study, what explains this discrepancy between what is known and what is done?
Filipa Pimenta (FP): Our study, which involved a representative sample of Portuguese adults, shows that 39% of this sample were effectively engaging in sustainable eating behaviors at the time of the study. Our results are very clear on one point: the risk perception associated with climate change did not predict the adoption of sustainable eating behaviors.
What related to a higher frequency of sustainable eating was the recognition of the advantages (and also the disadvantages) of eating more sustainably. In other words, those who perceive the climate threat better assess the pros and cons of the change, but this assessment does not automatically translate into behavior. This discrepancy is well known in behavioral science: perceiving a risk is different from being willing to act.
Between awareness and action lie factors such as confidence in one’s own ability to change (self-efficacy), the perceived costs of change (price, accessibility, convenience) and the social context. In our study, it was precisely self-efficacy and descriptive social norms (i.e., seeing significant people adopt these practices) that best explained the behavior.
The message for public policies is, therefore, straightforward: alarming is not enough; it is necessary to empower and facilitate.
According to what you discovered, the Portuguese who adopt the most sustainable dietary practices are those who already have a strong environmental and climatic awareness. What barriers are stopping others from joining this group and how can they be overcome?
Marta Uva (MU): There are barriers at several levels that prevent more people from joining that group. The perception of climate change risk is one of the factors conditioning this change, in the sense that even if there is perception of this risk and people understand the advantages of adopting sustainable eating behaviors to mitigate that risk, this intention does not always translate into behavior change, because the cost associated with that change significantly influences the decision to change.
Moreover, factors such as emotional eating and culture also condition this change. This happens because when eating habits are guided mainly by emotions, the perceived disadvantages of adopting sustainable eating patterns increase, which may be explained by the fact that emotional eating is associated with unhealthy eating patterns (i.e., the consumption of hyperpalatable foods, rich in sugar, salt and fat).
Regarding dietary culture, this is also a determinant aspect, in the sense that adults who spend more time with family or friends in social dining situations also identify more barriers to adopting sustainable eating. In other words, there is a tendency for people to maintain their eating habits throughout life and make dietary choices that fit their culture and, as such, they choose to buy products similar to what they have consumed all their lives, which can increase the perceived costs associated with change.
To overcome these barriers, it will be necessary to intervene at several levels. Social support has proven to be an important aspect in the sense that people who considered more important to rely on the support of close ones for their diets presented greater adoption of sustainable eating patterns, as well as more advantages to adopt them. However, for change to occur it should be promoted on a large scale. This would entail the development of national initiatives in which psychoeducational actions about the benefits of sustainable eating, about how to overcome barriers to adopting these behaviors and promoting the sharing of sustainable recipes could be carried out. Additionally, projects could be implemented in schools to educate the younger population about the importance of protecting the environment through sustainable consumption (for example, promoting plant-based diets in canteens).
The results of your study suggest that “pressure,” whether self-imposed or coming from outside, also plays an important role in adopting sustainable eating habits. But, interestingly, you found that excessive pressure can have precisely the opposite effect. Why?
FP: This was one of the most interesting results of the study. The so-called prescriptive norms (i.e., the perception that others expect us to adopt a given behavior or pressure us toward it) were associated with a greater recognition of the advantages of sustainable eating and a lower valuation of its disadvantages. But, paradoxically, they were associated with less actual behavior. In other words: social pressure convinces the head, but does not move the fork.
Psychology offers a plausible explanation: doing something just because others think we should do it compromises autonomy, one of the fundamental drivers of human motivation. When change is felt as imposed and not chosen, it can generate resistance, even in people who fully recognize the benefits of that change. There is an important lesson here for sustainability communication: moralizing or guilt-inducing campaigns that tell people what they should do run the risk of producing the opposite of the intended effect. Sustained motivation arises from informed choice, not from perceived obligation.
But, even so, social influence is important for promoting the dissemination of more sustainable eating practices, right? If done in the “right measure.”
MU: Without a doubt, social influence is essential to promote the adoption of sustainable eating practices.
In this study, we could observe that when Portuguese adults perceive that the important people in their lives are effectively taking more measures to combat climate change, the frequency with which they exhibit typical sustainable eating behaviors increases. In this sense, modeling (i.e., seeing the example of other people whose ideals and behaviors we value adopt these sustainable behaviors) leads to an increase in these behaviors in ourselves, exerting in this case a positive influence toward sustainability.
This modeling increases the person’s motivation toward this dietary pattern, facilitating the realization of behavioral change. Moreover, as already mentioned, pressure to adopt a sustainable diet may not have the same effect. Therefore, it seems more important and facilitative of behavioral change if this transition to a sustainable dietary pattern is done together, rather than if there is only pressure for it, without any visible example of it.
In the study, they suggest that a “relevant national initiative” could be the strengthening of the “perception of personal capability to adopt sustainable eating practices.” Does this mean that it is important to show that everyone can adopt these practices, that it is within reach for all? That even small, individual gestures can make a difference?
FP: Exactly. Self-efficacy for action (which is each person’s confidence in their ability to adopt and maintain sustainable eating behaviors) was one of the most consistent predictors in our study: it predicted more sustainable behavior, greater valuation of advantages and lower perception of disadvantages. And there is good news here: unlike other determinants, self-efficacy is trainable. It is built through successful experiences, and that is why small gestures matter so much.
Starting by replacing one meat-based meal per week, trying a vegetarian recipe, preferring local products on a shopping trip — each small successful step reinforces confidence for the next step. Conversely, messages that demand radical and immediate transformations tend to reduce perceived capability and paralyze.
A national initiative in this domain should, therefore, communicate feasibility: show that sustainable eating does not require perfection or heroic sacrifices, but rather gradual, concrete changes within reach of anyone, regardless of their income or literacy.
They also mention the importance of food literacy. In Portugal this is something that is still underdeveloped? Could it be promoted in schools, for example?
FP: Food literacy proved to be, in fact, an important factor. In our study, learning contexts (e.g., knowing where to find reliable information about food) predicted more sustainable behavior, greater valuation of advantages and lower perception of barriers. The same was true with attention to nutritional needs: those who consider the nutritional dimension of their diet adopt more sustainable practices.
This confirms that health and sustainability go hand in hand, and that quality information is a lever for both. Portugal has, indeed, relevant scientific contributions in this area, including instruments for assessing food literacy developed and validated for the Portuguese population by our team.
As for the “how”: yes, school is the privileged context. Educating from an early age (including through school cafeterias themselves, which can promote plant-based meals) creates habits and knowledge that endure. But food literacy does not end in childhood: it is also important to ensure reliable and accessible information sources for adults, combat nutritional misinformation, and involve health professionals in communicating about sustainable eating.
The study results indicate that Portuguese people, in general, do adopt sustainable eating practices, but in an occasional way, even though they understand there are more advantages than disadvantages to this adoption. There is, therefore, room and feasibility for improvements?
MU: Without a doubt. The results of this study allowed us to understand that the perception of advantages that Portuguese people have regarding adopting sustainable eating practices is high, yet this does not translate into the frequency that would be desirable.
This absence of behavior realization is explained in psychology by the intention-behavior gap, i.e., even if people have the intention and can understand the benefits of adopting a given behavior, they do not always manage to move from theory to practice. This can happen for various reasons, one of which is the perception of barriers that persist regarding the process of adopting that new behavior. In other words, the perceived costs associated with change (for example, the search for seasonal and organic products and also the prices associated with these products) may condition the realization of the change.
Nevertheless, this study concluded that there is room and feasibility for improvements in promoting sustainable eating practices among the Portuguese population, since there is already a perception of advantages of this behavior and it is practiced occasionally, and as such, to help the population in achieving this change and increasing the frequency of consumption of sustainable products, it is important to expand the perception of advantages and simultaneously reduce the perception of barriers, providing tips to overcome them and mobilizing the resources necessary to minimize the costs associated with these dietary practices.
How does changing eating habits help protect people and the planet and also contribute to the Sustainable Development Goals?
FP: The food system (from production to waste) is responsible for about a third of global greenhouse gas emissions, in addition to contributing to soil degradation and biodiversity loss. Simultaneously, inadequate dietary patterns are among the major threats to human health.
It is this double-edged aspect that makes food a unique lever: the same change that reduces the climate footprint (more plant-based foods, more local and seasonal products, less waste) also improves the health of those who adopt it.
The EAT-Lancet Commission has precisely demonstrated that it is possible to feed a growing world population healthily within the planet’s limits. From this perspective, changing eating habits directly contributes to several Sustainable Development Goals: health and well-being (SDG 3), responsible consumption and production (SDG 12), climate action (SDG 13), and even eradicating hunger through more equitable and resilient food systems (SDG 2). Few daily choices have such transversal reach.
Do you think the role of food (the choices we all make daily) in fighting planetary crises is receiving the attention it deserves? In Portugal, specifically, is it a topic that has the priority it should in efforts to protect the environment and climate?
FP: Honestly, no. The climate debate remains very centered on energy and transport, sectors obviously crucial; but food, although representing around a third of global emissions, rarely occupies a central place in climate policies or in public communication.
Our study was, in fact, motivated by this gap: as far as we know, it was the first investigation to try to explain, in a representative sample of the Portuguese population, what leads adults to adopt (or not) sustainable eating behaviors.
In Portugal, the topic has gained some visibility, but in a fragmented way, and without the necessary coordination between health, environment and agro-food policies. It is a missed opportunity, because we have particularly favorable conditions: a Mediterranean dietary tradition (recognizably healthy and sustainable) that is important to preserve and reactivate, quality local production and a population that, as our data show, already recognizes the advantages of the change. The task is to turn this potential into political priority, with concrete targets, involving the State, industry, schools and the health sector.
Should moving to more sustainable eating habits also be seen as a form of mitigating climate change and adapting the country to its effects? Is this being understood as such in Portugal’s climate, as well as food and agricultural policies?
FP: It should be seen as both, without a doubt. As mitigation, because reducing the consumption of products with a high carbon footprint and favoring plant-based, local and seasonal foods directly reduces emissions associated with the food system. As adaptation, because more diversified, more local food systems and less dependent on long supply chains make the country more resilient to the effects of climate change (which include droughts, extreme events, disruptions in international trade) that already affect agricultural production.
Regarding the second part of the question: it seems to us that this dual function is not yet fully reflected in Portuguese policies, where the climatic, dietary and agricultural dimensions seem to be treated separately.
In our study, we propose measures that bridge this gap: tax incentives for companies that market sustainable products, taxation of non-sustainable products to narrow the price gap, incentives for organic and sustainable farming, and school-based programs for food education.
Food is one of the rare domains in which climate policy, health policy and agricultural policy can converge, and all benefit.
