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.