Related Experiment Video
Updated: Jun 20, 2026
Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
The validity of BMI as an indicator of body fatness and risk among children
David S Freedman1, Bettylou Sherry
1Division of Nutrition, Physical Activity, and Obesity, Centers for Disease Control and Prevention, 4770 Buford Hwy, Mailstop K-26, Atlanta, GA 30341-3717, USA. dfreedman@cdc.gov
Insights
A high Body Mass Index (BMI) for age at or above the 95th percentile is a moderately sensitive and specific indicator of excess body fatness in children. This metric helps identify children at risk for obesity and related health issues.
Area of Science:
- Pediatrics
- Public Health
- Anthropometry
Background:
- Childhood obesity prevalence has tripled in 3 decades, with Body Mass Index (BMI) commonly used for assessment.
- BMI measures excess weight, not necessarily excess body fatness, necessitating evaluation of its accuracy in pediatric populations.
- Understanding BMI's relationship with body fatness and health risks is crucial for effective childhood obesity management.
Purpose of the Study:
- To evaluate the ability of BMI-for-age at or above the 95th percentile (Centers for Disease Control and Prevention [CDC] reference) to identify children with excess body fatness.
- To examine potential differences in BMI-body fatness associations across racial/ethnic groups.
- To determine if skinfold and circumference measurements offer additional insights into body fatness or health risks compared to BMI alone.
Main Methods:
- Review of existing literature on BMI, body fatness, and health risks in children.
- Analysis of the sensitivity and specificity of BMI-for-age percentiles in identifying excess adiposity.
- Assessment of the utility of skinfold and waist circumference measurements.
Main Results:
- BMI accuracy in reflecting body fatness varies; it's a good indicator in fatter children but can be influenced by fat-free mass in thinner children.
- BMI-for-age ≥95th percentile demonstrates moderate sensitivity (70%-80%) and high specificity (95%) for identifying excess body fatness.
- Children with high BMI are more prone to adverse health risk factors and adult obesity. Skinfold and waist circumference may aid in identifying at-risk children within the 85th-94th BMI percentiles.
Conclusions:
- BMI-for-age at or above the 95th percentile of the CDC reference population serves as a moderately sensitive and specific indicator of excess adiposity in children.
- High BMI in childhood is linked to increased health risks and future adult obesity.
- Additional anthropometric measures like skinfold and waist circumference can provide supplementary information for risk stratification.
Purpose Of Review:
Although the prevalence of childhood obesity, as assessed by BMI (kg/m(2)), has tripled over the last 3 decades, this index is a measure of excess weight rather than excess body fatness. In this review we focus on the relation of BMI to body fatness and health risks, particularly on the ability of BMI for age >or=95th Centers for Disease Control and Prevention [CDC] percentile to identify children who have excess body fatness. We also examine whether these associations differ according to race/ethnicity and whether skinfold and circumference measurements provide additional information on body fatness or health risks.
Results:
The accuracy of BMI varies according to the degree of body fatness. Among relatively fat children, BMI is a good indicator of excess adiposity, but differences in the BMIs of relatively thin children can be largely due to fat-free mass. Although the accuracy of BMI in identifying children with excess body fatness depends on the chosen cut points, we have found that a high BMI-for-age has a moderately high (70%-80%) sensitivity and positive predictive value, along with a high specificity (95%). Children with a high BMI are much more likely to have adverse risk factor levels and to become obese adults than are thinner children. Skinfold thicknesses and the waist circumference may be useful in identifying children with moderately elevated levels of BMI (85th to 94 th percentiles) who truly have excess body fatness or adverse risk factor levels.
Conclusion:
A BMI for age at >or=95th percentile of the CDC reference population is a moderately sensitive and a specific indicator of excess adiposity among children.
Related Concept Videos
01:24Obesity
01:29Reliability and Validity