The need to make more accurate grain demand (GD) forecasting has become a major topic in the current international grain security discussion. Our research aims to improve short-term GD prediction by establishing a multi-factor model that integrates the key factors: shifts in dietary structures, population size and age structure, urbanization, food waste, and the impact of COVID-19. These factors were not considered simultaneously in previous research. To illustrate the model, we projected China’s annual GDP from 2022 to 2025. We calibrated key parameters such as conversion coefficients from animal foods to feed grain, standard person consumption ratios, and population size using the latest surveys and statistical data that were either out of date or missing in previous research. Results indicate that if the change in diets continued at the rate as observed during 2013–2019 (scenario 1), China’s GD is projected to be 629.35 million tons in 2022 and 658.16 million tons in 2025. However, if diets shift to align with the recommendations in the Dietary Guideline for Chinese Residents 2022 (scenario 2), GD would be lower by 5.9–11.1% annually compared to scenario 1. A reduction in feed grain accounts for 68% of this change. Furthermore, for every 1 percentage point increase in the population adopting a balanced diet, GD would fall by 0.44–0.73 million tons annually during that period. Overlooking changes in the population age structure could lead to an overprediction of annual GDP by 3.8% from 2022 to 2025. With an aging population, China’s GD would fall slightly, and adopting a balanced diet would not lead to an increase in GD but would have positive impacts on human health and the environment. Our sensitivity analysis indicated that reducing food waste, particularly cereal, livestock, and poultry waste, would have significant effects on reducing GD, offsetting the higher demand due to rising urbanization and higher incomes. These results underscore the significance of simultaneous consideration of multiple factors, particularly the dietary structure and demographic composition, resulting in a more accurate prediction of GD. Our findings should be useful for policymakers concerning grain security, health, and environmental protection.

The estimation of China's future food grain demand has become vital input for designing grain security measures. Addressing the population's age-gender and urban-rural structures under three fertility policies scenarios together with concerns for balanced diets, we established a multi-factor driven model to forecast China's food grain demand (including staple food grain and feed grain) during 2021-2050. The three scenarios are as follows; the two-child fertility policy for couples when either the husband or the wife is from a single-child family (scenario 1); universal two-child policy (scenario 2), and no limitations on the number of children (scenario 3). The results show that in scenario 3, China's food grain demand would peak in 2030 at about 329.3 million tons, about 3.7 million tons higher than that in scenario 2, and 104.7 million tons lower than that estimated with the traditional per capita method. These findings indicate that the demographic transition for fertility policy adjustment is not the main impacting factor of China's food grain security from 2021 to 2050. We might overestimate food grain demand by about 15 percent if we ignored each age-gender and urban-rural structure of the population. Then it may lead to an oversupply of grain and accumulation of stocks, which would generate about 1 billion RMB annual inventory cost burden. An important complement to the demographic strategy would come from the adoption of the proposed Dietary Guideline for Chinese Residents (2019). It can make people much healthier and save about 7.5 percent of China's food grain consumption, reducing the pressure scarce supplies of water and land in the country.

The estimation of China's future food grain demand has become vital input for designing grain security measures. Addressing the population's age-gender and urban-rural structures under three fertility policies scenarios together with concerns for balanced diets, we established a multifactor driven model to forecast China's food grain demand (including staple food grain and feed grain) during 2021-2050. The three scenarios are as follows; the two-child fertility policy for couples when either the husband or the wife is from a single-child family (scenario 1); universal two-child policy (scenario 2), and no limitations on the number of children (scenario 3). The results show that in scenario 3, China's food grain demand would peak in 2030 at about 329.3 million tons, about 3.7 million tons higher than that in scenario 2, and 104.7 million tons lower than that estimated with the traditional per capita method. These findings indicate that the demographic transition for fertility policy adjustment is not the main impacting factor of China's food grain security from 2021 to 2050. We might overestimate food grain demand by about 15 percent if we ignored each agegender and urban-rural structure of the population. Then it may lead to an oversupply of grain and accumulation of stocks, which would generate about 1 billion RMB annual inventory cost burden. An important complement to the demographic strategy would come from the adoption of the proposed Dietary Guideline for Chinese Residents (2019). It can make people much healthier and save about 7.5 percent of China's food grain consumption, reducing the pressure scarce supplies of water and land in the country.Food security means a sufficient supply of foods and nutrients (FAO,1996), which indicates one needs a diverse, balanced diet containing various foods, such as those rich in vitamins, iron, and zinc. Close to 750 million -or nearly one in ten people in the world in 2019-were exposed to severe levels of food insecurity. The majority of the world's undernourished -381 million -are still found in Asia. At the global level, the prevalence of food insecurity at a moderate or severe level, and severe level only, is higher among women than men. The gender gap in accessing food increased from 2018 to 2019. If recent trends continue, the number of people affected by hunger will be 9.8 percent of the population by 2030, even without considering the potential impacts of the COVID-19 pandemic (FAO, 2020).China is the most populous country and the largest food consumer in the world. During 2013-2019, China's soybean, rice consumption accounted for about 30% of the total