Health care providers use a measurement called body mass index (BMI) tto figure out if a person is overweight. BMI is a calculation that uses your height and weight to estimate how much body fat you have.
BMI changes with age. That's why doctors plot and follow BMI over time. There are also different charts for girls and guys.
After calculating your BMI, a doctor or nurse will plot the result on a BMI growth chart. The BMI charts have lines for "percentiles." Like percentages, percentiles go from 0 to 100. The lines on the BMI growth charts show the 5th, 10th, 25th, 50th, 75th, 85th, 90th, and 95th percentiles. The 50th percentile line is the average BMI of the teens who were measured to make the chart.
When your BMI is plotted on the chart, the doctor can see how you compare with teens the same age and gender as you. Based on where your number plots on the chart, the doctor will decide if your BMI is in the underweight, healthy weight, overweight, or obese range.
There's a big range of normal on the chart:
Anyone who falls between the 5th percentile and the 85th percentile is a healthy weight.
If someone is at or above the 85th percentile line on the chart (but less than the 95th percentile) is overweight.
A BMI measurement at or over the 95th percentile line on the chart puts someone in the obese range.
Why Does It Matter?
A couple of extra pounds are not a health risk for most people. But being overweight or obese can lead to health problems, both physical and emotional.
It's very important to catch weight problems early, even while someone is still a teen. Being overweight as a teen makes a person more likely to be overweight as an adult. Also, many overweight teens can develop health problems like diabetes. Teens who are overweight also might be teased or bullied and are more at risk for depression.
If your doctor thinks your weight isn't in a healthy range, they will probably make specific eating and exercise recommendations or refer you to a dietitian or doctor who specializes in weight management.
It’s important to take a healthy approach to losing weight. If you’re concerned about your weight, talk to your doctor.