There have been multiple reports of decreases in obesity in specific populations and leveling off in others. However, in the U.S., despite recent declines in the prevalence among preschool-aged children, obesity among children is still too high. For children and adolescents aged two to 19 years, the prevalence of obesity has remained at about 17 percent and affects about 12.7 million children and adolescents for the past decade according to the Centers for Disease Control and Prevention (CDC).
Increasingly, severe obesity is being recognized as a distinct classification of excess weight. Originally defined as the 99th percentile BMI for age and gender, percentile classifications have been noted to perform poorly in statistical tests, and their use has not been recommended. Flegal et al. suggested use of percentages above the 95th percentile as a better means of quantifying children at higher levels of obesity, and this was recommended for use by the American Heart Association. Using nationally representative data, this designation of severe obesity finds associated cardiometabolic risk factors at higher prevalence. Other studies have also noted significant cardiometabolic risk, though definitions of severe obesity vary.
Data from 2011 to 2012 demonstrated an increase in severe obesity among children and adolescents from the previous 14 years. In particular, severe obesity (class II and III obesity) has significantly increased in adolescents and non-Hispanic, black children. Ongoing surveillance and analysis of obesity prevalence are paramount in order to best gauge progress of individual and public health efforts.
In 2013–2014, 17.4 percent of children met criteria for class I obesity, including 6.3 percent for class II and 2.4 percent for class III, none statistically different than 2011–2012. A clear, statistically significant increase in all classes of obesity continued from 1999 through 2014.