• Children;
  • obesity;
  • preschool;
  • severe obesity


What is already known about this subject

  • The prevalence of obesity in the United States has increased dramatically over the past three decades.
  • There is a growing spectrum of severe obesity among children and adolescents.
  • Obesity trends and race/ethnic differences may be evident at a young age.

What this study adds

  • Among children aged 3–5 years, the prevalence of obesity and severe obesity was higher in boys than in girls, and highest among children of Hispanic ethnicity.
  • Within this young age group, higher body mass index (BMI) was associated with greater height percentile.
  • Among obese children aged 5 years, provider recognition of obesity or elevated BMI was high, approaching 80% of children.


Early childhood adiposity may have significant later health effects. This study examines the prevalence and recognition of obesity and severe obesity among preschool-aged children.


The electronic medical record was used to examine body mass index (BMI), height, sex and race/ethnicity in 42 559 children aged 3–5 years between 2007 and 2010. Normal or underweight (BMI < 85th percentile); overweight (BMI 85th–94th percentile); obesity (BMI ≥ 95th percentile); and severe obesity (BMI ≥ 1.2 × 95th percentile) were classified using the 2000 Centers for Disease Control and Prevention growth charts. Provider recognition of elevated BMI was examined for obese children aged 5 years.


Among 42 559 children, 12.4% of boys and 10.0% of girls had BMI ≥ 95th percentile. The prevalence was highest among Hispanics (18.2% boys, 15.2% girls), followed by blacks (12.4% boys, 12.7% girls). A positive trend existed between increasing BMI category and median height percentile, with obesity rates highest in the highest height quintile. The prevalence of severe obesity was 1.6% overall and somewhat higher for boys compared with girls (1.9 vs. 1.4%, P < 0.01). By race/ethnicity, the highest prevalence of severe obesity was seen in Hispanic boys (3.3%). Among those aged 5 years, 77.9% of obese children had provider diagnosis of obesity or elevated BMI, increasing to 89.0% for the subset with severe obesity.


Obesity and severe obesity are evident as early as age 3–5 years, with race/ethnic trends similar to older children. This study underscores the need for continued recognition and contextualization of early childhood obesity in order to develop effective strategies for early weight management.