The trend of prevalence and severity of the overweight problem in young children, reduces the general quality of the future population to a certain extent, inducing a great risk to the sustainable development of health human capital stock in China.

To scientifically understand the spatio-temporal evolutionary patterns and future development trends of overweight rates among children under 5 in China, in order to provide support for controlling overweight in children, improve the efficiency of local governance and support for the implementation of precise interventions.

In April 2022, the 5 km×5 km gridded dataset in 105 middle-and low-income countries provided by the Institute for Health and Evaluation at the University of Washington (IHME) was used as the data source to extract the gridded data of overweight rates among children under 5 in China (excluding Hong Kong Special Administrative Region, Macao Special Administrative Region and Taiwan District) from 2000 to 2019 in this study. The average overweight rate of children under 5 from 2000 to 2019 was calculated pixel-to-pixel, the Theil-Sen estimator, Mann-Kendall test and Hurst index estimation method was used to characterize the spatio-temporal evolutionary patterns and future development trends among children under 5 pixel-to-pixel.

Overweight among children under 5 is more prevalent in most regions of Shandong Province, Hunan Province and local regions of Fujian Province, Guangdong Province, Hainan Province, Beijing Municipality and Tianjin Municipality during the 20-year period from 2000 to 2019, with the average overweight rate of children under 5 in Hunan Province reaching 29.42%. The area of the regions with significant increase in overweight rates among children under 5 accounts for 60.59% of the total area of the regions in the study (excluding regions with missing data) . The area of the central and eastern regions with a significantly increasing trend in the overweight rates among children under 5 accounts for a higher proportion of the total area of central and eastern regions (excluding regions with missing data) than the proportion accounted by the area of the western regions with a significantly increasing trend in the overweight rates among children under 5 of the total area of western regions (excluding regions with missing data) . The area of the regions with no significant change in the evolution trend of overweight rates accounts for 25.33% of the total area of the regions in the study, which is scattered in patches in parts of provinces, such as cities cluster in the middle reaches of the Yangtze River urban agglomeration. The area of the regions with significant change in the evolution trend of overweight rates accounts for 14.08% of the total area of the regions in the study, concentrated in some regions in the Xinjiang Uygur Autonomous Region, Qinghai Province, Sichuan Province and Yunnan Province in the west of China, and local regions of Hebei Province, Liaoning Province and Shandong Province in the east of China. According to the Hurst index, the area of the regions with persistent or trend-enhancing characteristics of the time series of overweight rates of children under 5 accounts for 84.87% of the total area of the regions in the study.

The spatial heterogeneity of overweight rates among children under 5 in China is obvious. There is a synergistic "U"-shaped association between the overweight rates of children under 5 and the overall level of regional development, the association implies a multi-stage, cascading developmental process of "declining stage of stunting" "stabilization stage" "rising stage of overweight with overnutrition". Focusing on social problems derived from the coupling of multidimensional factors of overweight in young children, the results of the study provide scientific support and policy reference for the government to formulate region-specific policies, build a three-level governance network of "government policy regulation - social concept penetration - family health management", and scientifically and precisely solve the overweight problem among children under 5.