From the Guidelines
Normal body mass index (BMI) for children is between the 5th and 85th percentiles.
BMI Classification for Children
- A BMI between the 5th and 85th percentiles is considered healthy 1
- A BMI between the 85th and 95th percentiles is considered overweight 1
- A BMI at or above the 95th percentile is considered obese 1
Key Points
- BMI is a reliable and valid measure of relative weight in children and is recommended for clinical use 1
- Age- and sex-specific BMI standards for the US population have been published as percentile growth curves by the Centers for Disease Control and Prevention 1
- The 95th percentile is likely to correspond to 130% of the ideal weight percentile, which corresponds to the child’s age- and sex-specific height percentile 1
- Children and adolescents with a BMI greater than the 95th percentile should undergo additional evaluation for obesity-related complications 1
From the Research
Definition of Normal Body Mass Index (BMI) for Children
- BMI is a measure of weight adjusted for height, calculated as weight/height(2) 2
- It is widely used as a screening tool for obesity in children, but has limitations in differentiating body fat from lean mass 2
BMI Percentiles for Children
- The World Health Organization recommends dividing children into percentile subgroups based on their BMI levels 3
- A BMI in the 25th-84th percentiles, within the accepted normal weight range, has been associated with an increased risk of elevated and high blood pressure among children and adolescents 3
- The Centers for Disease Control and Prevention's 85th to 94th percentiles are used to classify children as overweight, but this category may include children with normal body fatness 4
Limitations of BMI in Children
- BMI has low-moderate sensitivity and is problematic for clinical applications, as it cannot differentiate between fat and fat-free mass 2
- BMI-for-age percentile (BMI%) values may not be appropriate for tall or short children, as they can lead to incorrect classifications of overweight or underweight 5
- Other measures, such as waist circumference and waist-to-hip ratio, may be more accurate predictors of health risks in children 6
Classification of Body Fatness in Children
- BMI-for-age categories can correctly classify body fatness in children, but may not be diagnostic of level of adiposity 4
- About 77% of children with a BMI for age at or above the 95th percentile have an elevated body fatness, but levels of body fatness among children with a BMI for age between the 85th and 94th percentiles are more variable 4