The 2030 Agenda for Sustainable Development provides a global blueprint for dignity, peace, and prosperity for people and the planet, now and in the future. At its heart are the 17 Sustainable Development Goals (SDGs) as an urgent call to action by all countries—developed and developing—in a global partnership. The fact that food is the basic resource for life highlights the need for a comprehensive goal that can be achieved by reducing food waste, promoting healthy and balanced nutrition, raising awareness of the society on responsible food consumption and developing policies on food consumption by regulatory authorities in connection with ensuring the sustainability of food consumption. Therefore, ensuring sustainable food consumption can also be seen as a generic goal that can be supported by almost all SDGs.
In terms of the total world population, in some regions people suffer from hunger and poor nutrition because of the inaccessibility of safe food and water [9][10]. On the other hand, in some other regions people are overweight or obese and still have an increasing tendency to dietary shifts toward more sugar, animal protein, and trans fats [11]. There are approximately 155 million overweight or obese children on this planet, whereas 148 million children are undernourished [12]. To achieve sustainability in food consumption, food security and food safety issues should be considered together for both under- and over-consumption regions. Additionally, policymakers should pay more attention to complex interdependencies along the food chain and the complexities of modern global food systems [11].
There is also a moral aspect of the sustainable consumption of food because consumers are assumed to feel guilty or uneasy about wasting food [13][14][15]. However, in a recent study, Watson and Meah [16] report that consumers are not conscious of the environmental impacts of food waste, and only a few accept social impact as a reason for feeling guilty about their food waste. Additionally, the most important drivers for consumers that prevent food waste are found to be time and money. Nevertheless, food consumption is not only an environmental and economic problem but also a social and ethical one. According to Ayala [17], the perception of needs and desires; understanding of quality of life, progress, growth, and development in society; as well as cultural and ethical values, which are linked to consumption patterns, need to be emphasized.
In terms of the politics regarding sustainable consumption and production, food consumption is a major issue with its impact on the environment, individual and public health, social cohesion, and the economy. The sustainable consumption of food has been studied using various approaches. Some studies focused on meat consumption [34][35][36][37] and organic foods [38][39], while many others include environmental impact [40][41] and nutrition and health [42][43][44][45]. Some others have studied psychosocial determinants [46][47] as well as challenges and barriers [11][48]. Food consumption behavior on an individual level is mostly affected by cultural traditions, norms, fashion, and physiological needs. Grunert and Juhl [49] found that environmentally concerned people are more likely to buy more sustainable foods. Similarly, Nguyen et al. [39] also state that consumers with greater environmental concern are more likely to engage in environmentally friendly behaviors. Additionally, personal experiences such as tastes, health, and exposures, such as the availability of foodstuff, are other determinants. Furthermore, affordability, time availability, and household decision-making are effective in food consumption choices. Wongprawmas et al. [32] have also researched the determinants of food consumption choice and classified the factors as biological determinants (e.g., hunger, appetite, and taste), psychological determinants (e.g., mood, stress, and guilt), physiological determinants (e.g., access, education, and time), social determinants (e.g., culture, family, and peers), and economic determinants (e.g., cost, income, and availability). In addition, restricted food, green consumption, local consumption, and meat and protein substitutes are the derived factors for sustainable food consumption [50]. In demographic characteristics of households’ context, there are remarkable differences in terms of age as well as gender. For example, women tend to behave more sustainably [51][52][53]. In terms of age, there are controversial findings in the literature. For instance, Verain et al. [54] revealed that consumers with a less sustainable lifestyle are younger, while Azzurra et al. [51] found older people tend to be low-intensity consumers. Using these behavioral and demographic factors, some studies determined consumer typologies. De Barcellos et al. [55] identified consumer clusters of indifferents, environmentally conscious, or sustainability-oriented citizens, while Bulut et al. [56] classify consumers as “indifferents”, “sustainability enthusiasts”, or “sustainability pioneers”.
One of the primary consumption areas that has the largest impact on the environment is food consumption, which creates almost one-third of households’ total environmental impact [3]. A Life Cycle Assessment (LCA) defines the environmental impacts as an open loop with an approach called “cradle-to-grave.” LCA is suggested to be associated with only environmental components such as emissions, resource consumption, and environmental and health impacts associated with processes, products, or activities over their entire life cycles [57][58]. Consumers’ behaviors during the handling and preparation stages also cause environmental impacts, through storage, cooking, and dishwashing. In addition, consumers affect the environment with their nutrition styles and diets. It is proven by many researchers that consumers are either unaware of or underestimating the relationship between food consumption and climate change [59][60][61][62][63]. In the study of Truelove and Parks [62], a survey performed in the US found that only 10% have associated meat consumption with climate change. According to the study of Lea and Worsley [60], 22% of respondents in Australia believe that it would provide an environmental benefit to consume less meat. Heiskanen et al. [64] highlighted the role of education to promote sustainable consumption. There is no doubt that nutrition lifestyle not only has an impact on our health but also on the health of the planet. However, these prior studies have focused on the impact of food consumption on the environment. They are limited in explaining the influence of consumers’ knowledge and awareness on avoiding the unsustainable consumption of food.
Apart from environmental issues, many factors are identified in the literature in terms of motives and barriers to the sustainable consumption of food. Nutrition, health consciousness, social identity, concern for farmers, ethical concerns, food security, perceived availability, store reputation, and concerns about animal welfare are among the factors that influence the purchase of sustainable products, whereas high prices, time limit, access, lack of information, trust in labelling, limited marketing communication, and unawareness of environmental impact are the main barriers [61][69][70][71][72][73]. More specifically, Sidali et al. [74] found five main motivations of consumers toward sustainable foods: ethical attributes, naturalness, health-related aspects, terroir, and innovation. On the other hand, Gorgitano and Sodano [75] defined three main obstacles: the rebound effect, the knowledge-action gap, and the behavior-impact gap, which are limiting the sustainable consumption of food. At the individual level, lack of planning and purchasing, shopping routines, and lack of knowledge about the storage, preparation, and reuse of food were defined as the major causes of the unsustainability of food [15][76].
At this point, two broad behavioral strategies toward sustainable food consumption can be distinguished. The first strategy is to make sustainable product choices concerning the way the product is produced, such as organic, free-range, or fair-trade products. The second strategy is to choose sustainable dietary patterns concerning dietary composition, consumption curtailment, and reduced quantity within product categories such as reduced meat consumption [54]. In addition, consumer behavior is also affected by perceptual biases, such as the halo effect, where products that are perceived as ecological are also perceived as better in other aspects, such as nutrition, health, etc. For example, an eco-labeled product may not only taste better and have a smaller environmental impact than the non-labeled alternative, but it is also perceived to be healthier [77]. This situation also reflects the fact that consumers may have limited factual knowledge about the environmental impact (footprint) of food [78]. Another bias is “compensatory green beliefs,” according to which some consumers feel that every individual is entitled to a certain budget of resources, so that savings in some resources gives them the right to offset by consuming more of other resources (or increasing waste), within the limits of this budget. Combined with the “negative footprint illusion,” this idea most likely causes consumers to engage in acts of green consumption without actually lowering their total environmental impact [41]. Despite the huge body of psychological, sociological, and anthropological literature about consumer behavior, there is still confusion about how to induce long-term behavior changes for a healthier and more sustainable lifestyle. Nudging consumers toward a more sustainable lifestyle seems to be promising, but it still needs more research for specific guidelines for practitioners [79][80].