Entrenched obesity in childhood: findings from a national cohort study.

PURPOSE Given the high levels of obesity among U.S. children, we examine whether obesity in childhood is a passing phenomenon or remains entrenched into adolescence. METHODS Data are from the prospective nationally representative Early Childhood Longitudinal Study, Kindergarten Class of 1998-1999 (analytic sample = 6600). Anthropometrics were measured six times during 1998-2007. Overweight and obesity were defined using CDC cut-points. Entrenched obesity was defined as obesity between ages 5-9 coupled with persistent obesity at ages 11 and 14. RESULTS Almost 30% of children experienced obesity at some point between ages 5.6 and 14.1 years; 63% of children who ever had obesity between ages 5.6 and 9.1 and 72% of those who had obesity at kindergarten entry experienced entrenched obesity. Children with severe obesity in kindergarten or who had obesity at more than 1 year during early elementary were very likely to experience obesity through age 14, regardless of their sex, race, or socioeconomic backgrounds. CONCLUSIONS Prevention should focus on early childhood, as obesity at school entry is not often a passing phenomenon. Even one timepoint of obesity measured during the early elementary school years may be an indicator of risk for long-term obesity.