According to a new study, a child’s weight during kindergarten is a strong predictor of whether he or she will develop childhood obesity later in life. The study was published on January 30 in The New England Journal of Medicine by researchers at Emory University’s Rollins School of Public Health in Atlanta Georgia.
The study authors note that childhood obesity is increasing in the United States at an alarming rate; therefore, they conducted a study to determine at what tome point it first appears. They accessed data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998–1999, a representative prospective evaluation of 7,738 children who were in kindergarten in 1998 in the United States. Their goal was to determine the national incidence of obesity among these children during elementary school.
From 1998 through 2007, the children’s weight and height were measured seven times. Among the study group, 6,807 of the 7,738 children were not obese at baseline. The children were followed for 50,396 person-years. The investigators used standard thresholds from the Centers for Disease Control and Prevention (CDC) to define overweight and obese categories. They estimated the annual incidence of obesity, the cumulative incidence over a nine year period, and the incidence density (cases per person-years) overall; taken into account were sex, socioeconomic status, race or ethnic group, birth weight, and kindergarten weight.
The researchers found that when the children entered kindergarten (average age: 5.6 years), 12.4% were obese and another 14.9% were overweight. In the eighth grade (average age: 14.1 years), 20.8% were obese and 17.0% were overweight. From the fifth through the eighth grade, the annual incidence of obesity decreased from 5.4% during kindergarten to 1.7%. Overweight five-year-olds were four times as likely as normal-weight children to become obese (nine-year cumulative incidence: 31.8% vs. 7.9%), with rates of 91.5 vs. 17.2 per 1,000 person-years. Among children who developed obesity between the ages of five and 14 years, almost half had been overweight and 75% had been above the 70th percentile for body-mass index at baseline.
The authors concluded that obesity present between the ages of five and 14 years was more likely to have occurred at younger ages, primarily among children who were overweight when they entered kindergarten.
Take home message:
If you have a kindergartner who is overweight or obese, consult with a pediatrician or family physician to correct the situation. The longer an overweight condition is present, the more difficult it is to correct it.