Jan 9, 2017 Post By: Olivia Munger

Should I Worry About My Child's BMI? Body Mass Index Explained
BMI measurements can cause a lot of frustration and confusion for parents. Olivia Munger, a Registered Dietitian at Children's Health, shares her advice.

Q. My doctor says my child’s Body Mass Index (BMI) puts him in the overweight category, but I think he looks healthy. What does the BMI mean?

A. BMI measurements can cause a lot of frustration and confusion for parents. Kids are growing and need to eat well to gain weight during childhood. Like adults, kids come in all shapes and sizes, but a person’s weight in childhood is a strong predictor of their weight in adulthood, so it is important to monitor.

Olivia Munger is a Registered Dietitian in the Children’s Health Healthy Lifestyles Program.

It is hard to tell whether a child is overweight or obese just by looking at them. BMI is a ratio of height and weight that is a reliable way to estimate body fat in most children and teens.

Having an elevated BMI can increase the risk of developing type 2 diabetes, heart disease and high blood pressure. While culturally we may be okay with our child’s weight, we must consider the implications of their weight on their future health.

After a child’s BMI is calculated, it is measured against other children of the same sex and age to get a general picture of how their BMI compares. If your child’s weight is in the 85th percentile, their BMI is higher than 85% of children of their same sex and age.  

Weight Status Category

  • Underweight
    • Percentile Range
      • Less than the 5th percentile
  • Healthy weight
    • Percentile Range
      • 5th percentile to less than the 85th percentile
  • Overweight
    • Percentile Range
      • 85th to less than the 95th percentile
  • Obese
    • Percentile Range
      • Equal to or greater than the 95th percentile

The most important thing to know about the BMI is that it is a screening tool to identify potential weight problems, not a diagnosis. To diagnose a child as overweight or obese, your physician would take many other health factors into account. It is best to track it over time, because as your child grows, their body fat will change along with their BMI.

It is best to avoid using the terms overweight and obese with children and focus on being at a healthy weight. If you are concerned about how to help your child eat healthy, speak to your physician about resources and appropriate strategies.