Abstract
OBJECTIVE: This study examined secular trends in children's weight-status assessment, measured weight status, and ideal body image and their associations with subsequent changes in BMI, and it explored the differences between sociodemographic groups in China. METHODS: Longitudinal data from the China Health and Nutrition Survey of 4,605 children aged 6 to 17 collected between 2000 and 2011 were used and fitted to mixed models. RESULTS: From 2000 to 2011, overweight/obesity prevalence increased from 6.5% to 16.8%, but the percentage of children with self-perceived weight status as "fat" remained around 2.0%; 49.0% of children underestimated their weight status at baseline. Self-perceived body image of most participants was tracked during follow-up. Children who perceived themselves as being fat at baseline had a higher BMI increase over time during follow-up than those with an average body image (β [SE] = 0.99 [0.14] kg/m(2) per year, P < 0.001). Boys, young children, recent cohorts, and rural children had higher BMI increases than their counterparts. Over time, the thin-body silhouette became more desirable (8.4 percentage points higher, P < 0.001). CONCLUSIONS: Chinese children experience a large incongruence between their weight-status assessment, ideal body image, and actual weight status. Health promotion programs should examine their role in assisting children in developing a healthy body image and gaining greater self-motivation toward promoting a healthy lifestyle.