4.3.3.3 Shifting towards more plant-based diets

Reducing consumption of livestock products is the single most powerful leverage point for shrinking the environmental footprint of agriculture and food systems (including Land use changes). Reducing demand for unsustainable foods, especially in middle- and high-income countries (for example, shifting towards more plant-based diets can have a significant impact on GHG emissions and biodiversity loss, as well as having strong synergies with improving public health). The planetary health diet (PHD) is one proposal for an idealised reference diet that, if adopted, could feed a global population of 10bn in 2050, would significantly reduce the number of deaths from poor nutrition and would be environmentally sustainable (Willett et al., 2019). 

Dietary shifts require changes of normative consumer beliefs and behaviours, agricultural practices and policy. Changes to norms are nonlinear and dynamic – the more people who subscribe to a belief or behaviour, the more norms become visible and the more attractive the behaviour becomes to subsequent subscribers, creating a positive feedback loop (Figure 4.3.10) (Sparkman and Walton, 2017). Current norms in many countries hold that eating meat is tasty, ethical and normal. However, there are signs of changing beliefs (Dagevos and Voordouw, 2013). For instance, from 2008 to 2019 the UK has seen a 17 per cent decrease in meat consumption and worldwide participation in ‘Veganuary’ rose from just 1,280 in 2015 to 628,000 in 2022 (Veganuary, 2022).  

Agency – the belief that an individual’s change in dietary preferences will make a difference on a global scale and might encourage others to do so as well – is another element that can accelerate this change (Gaupp, Constantino, and Pereira, 2023). This belief may be driven by intrinsic motivation to try new, healthier food choices or a moral obligation to reduce animal suffering and/or environmental impacts, but can also be affected and amplified by socio-economic factors such as the influence of peers or exposure to media and information campaigns that advertise healthy eating. The non-linear spread of the GemüseAckerdemie, a non-profit organisation that focuses on establishing school gardens, fostering cooking skills, and dietary shifts in schools around Germany, Austria and Switzerland is an example for creating such reinforcing feedbacks. This rapidly growing project diffuses social norms, sustainable food knowledge, gardening and cooking capacities among children, parents and cooks in the schools and beyond. 

Experimental evidence shows norm changes can be accelerated by targeted nudging interventions, in which public procurement can play a powerful role. For example, a 2017 study of choice-architecture interventions examined the effect of increased availability of vegetarian meals in public cafeterias (Garnett et al., 2019). The study showed that increasing the proportion of vegetarian meals to 50 per cent of all meals offered across a number of trial cafeterias increased vegetarian sales by 40.8 per cent to 78.8 per cent. Moreover, the experiment had little effect on total sales and profit and therefore was an economically viable option for businesses. The dampening feedback of habitual food choices can be disrupted by choice-architecture interventions, while informational cascades and social contagion of norms work to reinforce willingness to try alternative, more sustainable diets. This works in synergy with the improvement of the alternative protein market, through feedback mechanisms such as economies of scale and learning by doing. In China and the US, a recent study shows that positive user experience is the most important predictor of an individual’s intentions to reduce meat consumption and support meat-reduction policies (Fesenfeld et al., 2023a), but that this choice was also affected both by social norms and exposure to information.