What should be understood to promote environmentally sustainable diets?

An environmentally sustainable diet plays an increasingly significant role in reducing environmental impacts from the consumer side. The prominent environmentally sustainable dietary choices that have been discussed in recent years include organic food, local seasonal food, protein alternatives, plant-based diets, sustainable packaging, sustainable cooking, sustainable storage, and food waste reduction. However, the majority of related studies have focused on only one single environmentally sustainable dietary choice, and comprehensive considerations of the environmental impacts, psychological factors, and practices related to different dietary choices are still limited. Thus, we take a broad perspective on this issue and aim to provide a theoretical foundation for policy makers and consumers to make environmentally friendly choices. This review aims to answer the following three questions: (1) Which dietary choices result in lower environmental burdens than conventional diets? (2) How do psychosocial factors influence environmentally sustainable dietary choices? (3) What interventions are effective in changing consumers' dietary choices? The results showed that there is a gap between the actual and perceived environmental impacts of dietary choices, including organic food, local seasonal food and food packages. Although transitioning from a meat-based diet to a plant-based one, reducing food waste, and adopting efficient cooking methods can bring considerable environmental benefits, barriers such as inconvenience, price, and neophobia significantly hinder behavior changes. Besides, the influence of environmental concern on most environmentally sustainable diets is weak, whereas health concern plays a significant role. In practice, a long-term change in dietary structure could be achieved by addressing cultural barriers and social norms, through the cooperation of governments, retailers, food producers, and consumers.