**Background:** Since China's reform and opening up, agricultural productivity improvements have significantly reduced hunger, with food deficiency falling below 2.5% by 2019. However, internal pressures (population growth, resource constraints, environmental limits) and external risks (trade frictions, COVID-19) continue to threaten food security. Most existing studies focus narrowly on grain crops, neglecting the diversification of diets toward animal products. This study adopts a calorie-based approach to unify six food categories and analyze spatio-temporal patterns of food production and supply-demand equilibrium across China from 1978 to 2020.
**Methods:** The study constructed a database covering 26 food items in six categories (grain crops, oil crops, sugar crops, vegetables and fruits, livestock, aquatic products) using provincial-level data from the China Rural Statistical Yearbook, China Agricultural Statistics, and other sources. Calorie conversion used edible portion proportions and calorie content from the Chinese Food Composition Table (6th edition). Local food supply was estimated by deducting feed use (e.g., 66% for maize, 11% for soybean) and food loss and waste (loss ratio declining from ~16.13% in 1978 to 8.95% in 2020; waste fixed at 10%). The feedable population was calculated using an average daily calorie requirement of 2350 kcal/person/day. Spatio-temporal evolution was analyzed at four scales: national, production and marketing sub-regions (Main Producing Region, Main Marketing Region, Balanced Production-Marketing Region), seven physical geographic divisions, and 31 provinces. Linear regressions and significance tests were performed, and the geographical center of gravity model was used to track spatial shifts in food calorie supply and population.
**Key Results:** Nationwide food calorie production increased from 819.85 × 10^12 kcal in 1978 to 2172.07 × 10^12 kcal in 2020, a growth rate of 31.7 × 10^12 kcal/year (p < 0.001). The Main Producing Region contributed 66.40% of total calories in 1978 and 73.54% in 2020, while the Main Marketing Region's share fell from 18.70% to 7.47%. Grain crops dominated but declined from 90.41% of total calories in 1978 to 65.52% in 2020, while livestock rose to 11.41% and vegetables/fruits to 10.82%. At the provincial level, major producing provinces shifted northward from Jiangsu, Guangdong, Hubei, Hunan, and Sichuan in 1978 to Heilongjiang, Shandong, and Henan by 2020. Three provinces (Beijing, Shanghai, Zhejiang) showed continuous decreases in calorie production. China's food production began showing a national calorie surplus in 1992, potentially feeding 1.92 billion people by 2020. However, the Main Marketing Region had a deficit equivalent to 150 million people in 2020, and North China remained consistently in short supply. The center of gravity for calorie supply moved 204.67 km northeast (from Hubei to Henan), while the population center moved 63.75 km southwest, creating a spatial mismatch.
**Clinical Implications:** While not a clinical study, this research has implications for public health nutrition and food security policy. The calorie-based approach reveals that despite national surpluses, regional disparities in food self-sufficiency persist, with 15 provinces unable to meet their own food calorie needs in 2020. The spatial mismatch between food production (shifting northeast) and population (shifting southwest) increases reliance on long-distance food transport, storage, and logistics, which has implications for food waste, greenhouse gas emissions, and supply chain resilience. The study notes that micronutrient deficiencies remain a concern in China—for example, dietary fiber intake of 10.4 g for Chinese residents aged 2+ years (2015–2017) was lower than in the US (17.5 g) and the Netherlands (19.8 g). These findings underscore the need for integrated agricultural and nutritional policies that address both calorie sufficiency and dietary quality.