Identification of Critical Intervention Windows for Central Obesity from Childhood to Early Adulthood: A 30-year Longitudinal Study in China.

Objective: To characterize long-term transition probabilities in waist circumference (WC) status from childhood into early adulthood and identify critical age windows for the development, persistence, and reversal of central obesity. Methods: Using the China Health and Nutrition Survey data (1993-2022), 7,007 WC measurements from 2,440 participants aged 6-17 years at baseline were analyzed. Participants were grouped by baseline age: 6-11, 12-14, and 15-17 years. Generalized linear mixed-effects models were used to estimate WC transition probabilities, adjusting for sociodemographic factors. Results: Central obesity prevalence increased from age 6, declined in early adulthood (approximately 22 years), and subsequently increased again. The 6-14-year age window exhibited dynamic, bidirectional transitions; specifically, the 10-year reversal probabilities from central obesity to normal WC were 44.19% (ages 6-11) and 41.39% (ages 12-14), decreasing to 26.93% for ages 15-17. Among those aged 15-17 years with central obesity, boys had a > 80% probability of maintaining increased WC for 20 years. Conclusion: Ages 6-14 years represent a critical "reversal period" for central obesity. Interventions should prioritize this window using age- and sex-specific strategies to maximize normalization and curb long-term obesity risk.