It is now known that our current food systems create several environmental challenges - from land-use change and biodiversity loss to the depletion of freshwater sources and climate change (Springman, et al,. 2018b). Historically, agriculture as an economic activity has generated a large portion of national GDP for many countries (Mbow et al., 2019), while per capita food supply has jumped by 30% since 1961 (Mbow et al., 2019, p441). However, in addition to this monetary value created by our food systems, we have created a social hierarchy from our food systems and have integrated what we eat into our cultures.
It is, therefore, in this context that sustainable diets arise as a potential solution to addressing environmental challenges. The meaning of “sustainable diets” is one that lacks consensus in the literature. In its recent report, the IPCC considers “low-GHG-emission diets” (Mbow et al., 2019, p499). The Food and Organisation of the United Nations (FAO) defined “sustainable diets” as those with “low environmental impacts which contribute to food and nutrition security and to healthy life for present and future generations [...they] are protective and respectful of biodiversity and ecosystems, culturally acceptable, accessible, economically fair and affordable; nutritionally adequate, safe and healthy…” (FAO, 2010).
The IPCC, famously, reported the importance of consumers in mitigating climate change (demand-side mitigation). In relation to the food we eat, this found that vegan, vegetarian and flexitarian diets are the best in overall resolving some of the environmental challenges created by our current food systems.
Greenhouse Gas Emissions
According to the IPCC, the consumption of sustainable diets is a major opportunity for reducing GHG emissions (high confidence) (Mbow et al., 2019). Dietary changes have the potential to address environmental challenges when animal products (environmentally-intensive foods) are replaced by less intensive food types – such as certain fruits, grains and vegetables. This not only has the potential to drastically reduce environmental pressures on GHG emissions by 29%, but may also carry socio-economic benefits (Springmann et al., 2018b). In the USA, a shift in consumption to more sustainable diets signalled a potential reduction of GHG emissions from food production (Birney et al. 2017). The impacts of flexitarian diets, and by extension the impacts of sustainable diets, are shown to carry strong benefits when applied in high-income countries (Springmann et al., 2018a). However, the same paper found that replacing animal products with plant-based ones had little effectiveness in countries with low consumption of animal-source foods (Springmann et al., 2018a).
On the other hand, the transition to sustainable diets is less clear-cut in relation to land-use. One of the notorious arguments made by people who eat meat is that reducing meat consumption will not benefit land-use as the increase in plant-based alternatives will increase the need for agricultural land. In a study carried out in Sweden, a 50% reduction of meat consumption replaced by domestically grown grain legumes would lead to an estimated reduction of land-use by 23% (Röös et al., 2020). The quadruple increase of Swedish cultivation of grain legumes meant that 1% of Swedish arable land would be used, however, due to the reduction in domestic chicken and pork production - and therefore the reduced need for animal feed - there would be enough agricultural land to enable the transition (Röös et al., 2020).
A systematic review carried out by Aleksandrowicz and colleagues found that plant-based diets and diets with meat-alternatives had median reductions of -28% for land-use, where vegan diets provided the most environmental benefits (Aleksandrowicz et al., 2016). However, some of the studies examined in the paper, showed that certain types of nuts and fruits had an environmental impact that was similar or higher than that of meat (Aleksandrowicz et al., 2016, p8). This may encourage some opponents to give themselves a pat in the back; however, research has shown that a combination of measures in addition to sustainable diets may do the trick. For instance, better waste management and technological changes to increase the efficiency of production; a combination of which is shown to result in the largest reductions in land-use and GHG emissions (Springmann et al., 2018b, p520).
A Eurocentric perspective
It is suggested that sustainable diets may be problematic in the context of low and middle-income countries that struggle with nutrition transitions (Fanzo, 2019). This is indicative of the complex relationship between sustainable and healthy diets and the role that historical development plays in addressing environmental challenges. Such nuanced recommendations often come from a Eurocentric stance and ignore the intricate relationships between food and other social factors such as income per capita and accessibility, making the applicability of sustainable diets more challenging at a larger scale.
Further, ethical concerns arise in relation to consumer preferences and the potential limitations on self-liberties (Fanzo, 2019). Meat, dairy and fish are valued in Western society and are foods we have placed significance importance on in relation to social standing (Popkin, 2011, p17). These consumption patterns and expectations may be difficult to refashion overnight.
Feasibility of a demand-side approach
Consumer preferences drive this approach and may be the largest pitfall thereof. The switch to sustainable diets is inherently reliant on consumers and their motivations to adopt a sustainable lifestyle. Due to the social and cultural significance attached to food (Mbow et al., 2019), it may be less socially acceptable to reduce meat consumption in diverse contexts. The studies carried out that illustrate the potentially important role of sustainable diets in addressing environmental challenges are based on some fundamental assumptions - such as consumers’ willingness to quickly change their behaviour patterns, and their motivations for doing so - while ignoring the subjective nature around the social perception of food.
The transition and attempts to cut pollution in livestock farming is already underway in the Netherlands, where to meet national targets, the government announced a €25bn plan to reduce livestock numbers by 30% (Levitt, 2021). This led to strong opposition from Dutch farmers who protested the measures through multiple blockades this summer, as they felt that their sector was singled out (Boztas, 2022). This social upheaval may be demonstrative of some of the potential justice concerns that may arise in relation to the transition to sustainable diets for addressing environmental concerns. The drastic reduction in demand means an equally as drastic drop in profits and employment for those involved in the livestock industry. As the IPCC notes, there is limited research on the ways that an unjust transition can be mitigated (Mbow et al., 2019, p514). For instance, for the effective implementation of a transition to sustainable diets, investment in incentive schemes for farmers are necessary (Springmann et al., 2018b, p523).
Sustainable diets may be better paired with alternative technologies and other behavioural changes. For instance, the Western culture around food waste and the role we as consumers play in perpetuating an unsustainable system is unquestionable. However, behavioural, social and cultural change cannot happen overnight.
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