Body mass index (BMI), which measures weight in relation to height, is used to identify a possible weight problem for a child older than 2 years old.

A child age 2 to younger than 5 who has a BMI:

• Below the 3rd percentile is at risk for underweight.
• In the 3rd percentile to below the 85th percentile is at a healthy weight.
• In the 85th percentile to the 97th percentile is at risk for overweight.
• Above the 97th percentile to the 99.9th percentile is overweight.
• Above the 99th percentile is obese.

A child ages 5 to 19 who has a BMI:

• Below the 3rd percentile is at risk for underweight.
• In the 3rd percentile to below the 85th percentile is at a healthy weight.
• In the 85th percentile to the 97th percentile is overweight.
• Above the 97th percentile to the 99.9th percentile is obese.
• Above the 99th percentile is severely obese.

Children grow at a different rates. Your doctor can tell you if your child's weight is a concern.

In some cases, a child may be considered at risk for overweight or overweight because he or she has a large amount of body fat (adipose tissue). But not all children with BMIs in the 85th to 97th percentile have too much body fat. For instance:

• A child who has grown consistently at a higher percentile for most of his or her life may just be bigger than other children of the same age due to genetics.
• Before and during puberty, it is normal for children to have a significant gain in weight before beginning to grow in height. This can temporarily increase a child's BMI.
• Children who are very muscular (for instance, children who are very active in sports) may have a higher BMI but have normal or even low amounts of body fat.