Rethinking workable solutions for saving cultivated land use and enhancing climate adaptation through diet shifts

China’s rapid economic development has profoundly transformed residents’ dietary patterns, which has not only intensified pressure on cultivated land but also posed severe challenges to climate change response. Establishing a sustainable dietary system helps ensure China’s food and nutrition security. In this study, we designed nine types of dietary shift patterns and developed a multi-regional input-output model at high sector resolution to assess the changes of cultivated land use and greenhouse gas (GHG) emissions. Moreover, we explored the linkages among nutritional quality, food affordability, cultivated land use, and GHG emissions across different provinces and proposed differentiated strategies to facilitate dietary transition. We found that adopting alternative diets increased the intake of beneficial nutrients but also inevitably increased the intake of restricted-intake nutrients. Environmental impact analysis reveals that the consumption of grain and meat contribute to 70 % of cultivated land occupation and 90 % of GHG emissions. Except for the High-Meat scenario, the reduction in meat consumption has positive effects in all other dietary scenarios, leading to 6–35 % decrease in embodied cultivated land and 11–43 % reduction in embodied GHG emissions. Moreover, the affordability assessment indicates that western regions of China face greater affordability challenges in diet transition. Our findings highlight the complex trade-offs and synergies among nutritional quality, food affordability, cultivated land use, and GHG emissions through diet shifts. Developing differentiated dietary transition strategies is crucial for achieving multiple co-benefits.