BMI Home > BMI and Obesity
What do obesity and BMI have to do with each other? BMI (short for body mass index) is a simple method used to measure body fat based on a person's height and weight. BMI is one factor healthcare professionals consider when measuring obesity. A body mass index of 18.5 to 24.9 is considered normal, 25 to 29.9 is considered overweight, and a BMI of 30 or higher is considered obese. Current statistics indicate that approximately 61 million American adults are obese.
Nearly twothirds of adults in the United States, or about 130 million adults, are overweight (defined as a BMI between 25.0 and 29.9). Nearly 61 million of those adults are obese (defined as a BMI greater than or equal to 30).
Even more startling is that approximately 15 percent of children and adolescents are overweight, and another 15 percent are at risk for being overweight (BMI for age between the 85th and 95th percentile). Child obesity is a growing concern in the United States. An alarming number of children are obese and developing diseases normally seen in adulthood.
Body mass index, or BMI for short, is a tool that is used to measure a person's weight status. To calculate BMI, only a person's weight and height are needed. Because of this simplicity, BMI is the most routinely used method to measure a person's weight status.
There are a few ways to determine your BMI:
 Calculate BMI using the BMI formula
 Use the BMI chart
 Use the BMI calculator.
Any of these three methods will get the same BMI result. Once the BMI number is determined, it can be interpreted for adults using standard weight status categories that are the same for all ages and for both men and women. The standard weight status categories associated with BMI ranges for adults are shown below:
BMI

Weight Status

Below 18.5

Underweight

18.5 – 24.9

Normal

25.0 – 29.9

Overweight

30.0 and Above

Obese

For children and teens, after determining the BMI, the BMI number is plotted on the BMIforage growth charts (for either girls or boys) to obtain a percentile ranking. The percentile indicates the relative position of the child's BMI number among children of the same sex and age.
BMIforage weight status categories and the corresponding percentiles are shown in the following table:
Weight Status Category

Percentile Range

Underweight

Less than the 5^{th} percentile

Healthy weight

5^{th} percentile up to the 85^{th }percentile

At risk of overweight

85^{th} to less than the 95^{th} percentile

Overweight

Equal to or greater than the 95^{th} percentile
