Defining Childhood Obesity

Weight Measurement

The World Health Organization, U.S. Centers for Disease Control and Prevention, and International Obesity Task Force each have definitions of overweight and obesity in children and adolescents (see table). At different ages, these criteria give somewhat different estimates of overweight and obesity prevalence.

In preschool girls, for example, the World Health Organization body mass index (BMI) cut points for overweight and obesity are much higher than those of the International Obesity Task Force. One recent Czech study found that using the International Obesity Task Force cutoff, about 15 percent of 5-year-old girls were overweight; by the World Health Organization cutoff, only about 3 percent were overweight. (1)

In older adolescents, meanwhile, the U.S. Centers for Disease Control and Prevention’s “normal” weight range includes BMIs that are greater than 25, and overweight includes BMIs that are greater than 30 levels that, if maintained into young adulthood, would correspond to overweight (not normal weight) and obesity (not overweight). There’s clearly a need to harmonize these international standards for childhood obesity.

Organization Definition of Childhood Obesity
World Health Organization WHO Child Growth Standards (birth to age 5) (2)

  • Obese: Body mass index (BMI) > 3 standard deviations above the WHO growth standard median
  • Overweight: BMI > 2 standard deviations above the WHO growth standard median
  • Underweight: BMI < 2 standard deviations below the WHO growth standard median

WHO Reference 2007 (ages 5 to 19) (3)

  • Obese: Body mass index (BMI) > 2 standard deviations above the WHO growth standard median
  • Overweight: BMI > 1 standard deviation above the WHO growth standard median
  • Underweight: BMI < 2 standard deviations below the WHO growth standard median
U.S. Centers for Disease Control and Prevention CDC Growth Charts (4)
In children ages 2 to 19, BMI is assessed by age- and sex-specific percentiles:

  • Obese: BMI ? 95th percentile
  • Overweight: BMI ? 85th and < 95th percentile
  • Normal weight: BMI ? 5th and < 85th percentile
  • Underweight: BMI < 5th percentile

In children from birth to age 2, the CDC uses a modified version of the WHO criteria (5)

International Obesity Task Force
  • Provides international BMI cut points by age and sex for overweight and obesity for children age 2 to 18 (6)
  • The cut points correspond to an adult BMI of 25 (overweight) or 30 (obesity)


1. Monasta L, Lobstein T, Cole TJ, Vignerov J, Cattaneo A. Defining overweight and obesity in pre-school children: IOTF reference or WHO standard? Obes Rev. 2011;12:295-300.

2. de Onis M, Onyango AW, Borghi E, Siyam A, Nishida C, Siekmann J. Development of a WHO growth reference for school-aged children and adolescents. Bull World Health Organ. 2007;85:660-7.

3. World Health Organization. World Health Organization Child Growth Standards. 2006. Accessed March 5, 2012.

4. Kuczmarski R, Ogden CL, Grummer-Strawn LM, et al. CDC Growth Charts: United States. Hyattsville, MD: National Center for Health Statistics; 2000.

5. Grummer-Strawn LM, Reinold C, Krebs NF. Use of World Health Organization and CDC growth charts for children aged 0-59 months in the United States. MMWR Recomm Rep. 2010;59:1-15.

6. Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ. 2000;320:1240-3.

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