Rapidly rising incomes and increased urbanization are driving global dietary transition in which traditional diets are replaced by diets higher in refined sugars, refined fats, oils and, meat. This is closely related to environmental and human health. Considering the large urban population, distinctive urbanization processes, preference for refined foods, and serious environmental challenges, such trends are particularly important for China. Currently, 6.4% of Chinese adults are obese and 34.3% are overweight, which means China became a country with the highest number of obese and overweight people in the world. Excess food intake is considered the fundamental cause of obesity and overweight. At the same time, excessive food intake and unsustainable diet structure will expand the burden on the natural environment and climate change, as well as threaten food security. The environmental impacts of diet patterns and the health consequences of unsustainable diets are recognized as global issues, yet the environmental implications of excess food intake have been less well studied. Building on the representative resident survey data from the China Health and Nutrition Survey, this study estimates in detail the excessive food intake based on the human metabolic theory. Then it assesses its environmental impact based on the life cycle assessment. Results showed an excessive intake of nearly 11.70 Mt of food for one year in China, accounting for approximately 2.05% of the total food production in China. The estimated energy, water, carbon and ecological footprints resulting from excessive food intake amounted up to 10.72 Mtce, 300.82×109 m3, 37.53 Mt CO2 eq and 522.99×109 m2, respectively. Thus, excessive food intake and its corresponding environmental impact have exceeded the amount and impact of avoidable household food waste at home in China. Cereals and meats have a dominant role in excessive food intake and related environmental impact. Moreover, significant differences in excess food intake among populations with different demographic characteristics and urbanization levels, reflected that excess food intake and its environmental impacts were higher among people living in rural areas and men. This study provides the first estimate of the environmental cost of excessive food intake in China and highlights the importance of considering it in pathways to simultaneously improve both environmental and human health.