In a 2014 blog post, we discussed a CDC report found that childhood obesity among American two- to five-year-olds had dropped a remarkable 43% from 2003-2004 to 2011-2012. However, as reported in the Washington Post, a new study published this month in Obesity found an opposite trend. The study looked at the same data from the 2014 study and data for the intervening years and preceding years going back to 1999. The researchers found that, contrary to the CDC’s findings, obesity has not been on a sustained decline among this cohort and most recently, it is once again on the rise.
How did the same data yield such different results upon re-examination? According to the CDC report, the obesity rate dropped from approximately 14% in 2003-2004 to 8% in 2011-2012. However, the latter study noted that the average obesity rate for boys and girls this age from 1999-2000 had been approximately 10.7%, which meant it spiked almost 3.5% in the years preceding the earliest CDC data, and after dropping for a few years, the average spiked once again to approximately 12% in 2009-2010 before again dropping down to 8% in 2011-2012. The most recent data (2013-2014) shows the rate is once again on a gradual rise (9.25%). It’s worth noting that the data, when broken down by gender shows a mostly downward trend for girls, while for boys the rate has risen and dropped more erratically.
In short, the study notes, “the significant decline previously reported in prevalence [of obesity] for 2- to 5-year olds for 2003-2012 is not evident in our results, for girls or boys, using all data from 1999 to 2014.” As the study’s author told the Post, “...when you look at trends, it matters where you start.”