Importance: Childhood obesity is the focus of public health efforts and accurate estimates of the prevalence and severity of obesity are needed for policy decisions and directions for future research.
Objective: To examine the prevalence of obesity and severe obesity over time for 14 years of the continuous National Health and Nutrition Examination Survey, 1999 to 2012, and to examine differences in the trends by age, race/ethnicity, and sex.
Design, setting, and participants: Representative sample (N = 26 690) of children in the United States, ages 2 to 19 years, in repeated cross-sections of the National Health and Nutrition Examination Survey, 1999 to 2012.
Main outcomes and measures: Prevalence of overweight (body mass index [BMI] ≥ 85th percentile), obesity (BMI ≥ 95th percentile for age and sex), class 2 obesity (BMI ≥ 120% of the 95th percentile or BMI ≥ 35), and class 3 obesity (BMI ≥ 140% of the 95th percentile or BMI ≥ 40).
Results: From 2011 to 2012, 17.3% (95% CI, 15.3-19.3) of children in the United States aged 2 to 19 years were obese. Additionally, 5.9% (95% CI, 4.4-7.4) of children met criteria for class 2 obesity and 2.1% (95% CI, 1.6-2.7) met criteria for class 3 obesity. Although these rates were not significantly different from 2009 to 2010, all classes of obesity have increased over the last 14 years.
Conclusions and relevance: Nationally representative data do not show any significant changes in obesity prevalence in the most recently available years, although the prevalence of obesity may be stabilizing. Continuing research is needed to determine which, if any, public health interventions can be credited with this stability. Unfortunately, there is an upward trend of more severe forms of obesity and further investigations into the causes of and solutions to this problem are needed.