Body Mass Index (BMI)
Risk of Associated
Disease According to BMI and Waist Size
|| ||Waist less than or equal
40 in. (men) or
35 in. (women)
|Waist greater than|
35 in. (women)
|18.5 or less ||Underweight ||-- ||N/A|
|18.5 - 24.9 ||Normal ||-- ||N/A|
|25.0 - 29.9 ||Overweight
|30.0 - 34.9 ||Obese ||High ||Very High|
|35.0 - 39.9 ||Obese ||Very High ||Very High|
|40 or greater ||Extremely Obese ||Extremely High ||Extremely High|
Body Mass Index (BMI) and Waist Circumference (WC) can be useful measures of determining obesity and increased risk for various
diseases. According to the National Institutes of Health, a high WC is associated with an increased risk for type 2 diabetes,
dyslipidemia, hypertension and cardiovascular disease when BMI is between 25 and 34.9. (A BMI greater than 25 is considered
overweight and a BMI greater than 30 is considered obese.) WC can be useful for those people categorized as normal or overweight
in terms of BMI. (For example, an athlete with increased muscle mass may have a BMI greater than 25 - making him or her overweight
on the BMI scale - but a WC measurement would most likely indicate that he or she is, in fact, not overweight). Changes in
WC over time can indicated an increase or decrease in abdominal fat. Increased abdominal fat is associated with an increased
risk of heart disease.
BMI for Children and
(BMI for Children and
Teens is sometimes referred to as "BMI-for-age.")
BMI is Used Differently with Children
Than it is With Adults
In children and teens, body mass index is used to assess underweight, overweight, and risk
for overweight. Children's body fatness changes over the years as they grow. Also, girls and boys differ in their body
fatness as they mature. This is why BMI for children, also referred to as BMI-for-age, is gender and age specific.1,
2 BMI-for-age is plotted on gender specific growth charts. These charts are used for children and teens 2 – 20
years of age. For the 2000 CDC Growth Charts and Additional Information visit CDC's National Center for Health Statistics.
Each of the CDC BMI-for-age gender specific charts
contains a series of curved lines indicating specific percentiles. Healthcare professionals use the following established
percentile cutoff points to identify underweight and overweight in children.
| ||Underweight ||BMI-for-age
< 5th percentile|
| ||At risk of overweight ||BMI-for-age 85th percentile|
to < 95th percentile
| ||Overweight ||BMI-for-age > 95th percentile|
|BMI decreases during the preschool years, then increases into adulthood. The percentile curves
show this pattern of growth. || |
|What does it mean if my child is in the 60th percentile?|
The 60th percentile means that
compared to children of the same gender and age, 60% have a lower BMI.
Let's look at the BMI
for a boy as he grows. While his BMI changes, he remains at the 95th percentile BMI-for-age.
|2 years ||19.3 ||95th|
|9 years ||21.0 ||95th|
|13 years ||25.1 ||95th|
We see how the boy's BMI declines during his preschool
years and increases as he gets older.
is BMI-for-age a useful tool?
BMI-for-Age is used for children and teens because of their rate of growth and
development. It is a useful tool because
- BMI-for-age provides a reference for adolescents
that can be used beyond puberty.
- BMI-for-age in children and adolescents compares
well to laboratory measures of body fat.
- BMI-for-age can be used
to track body size throughout life.
For the 2000 CDC Growth Charts and Additional
Information visit CDC'S National Center for Health Statistics.
For more information on how to use the growth
charts visit The Growth Chart Training Modules.