How can you tell if you are at a healthy weight? Chances are, if you follow nutrition eating guidelines and get plenty of exercise, you're doing just fine. However, there are an increasing number of children becoming overweight, obese, and some are even underweight. About 15% of kids in the United States are overweight. That may not sound like a lot, but being overweight can have a big impact on your health, so it's important to start healthy habits while you're young.

Doctors have several ways they can check to make sure you're at a healthy weight. One way is checking your BMI. BMI is a mathematical calculation that uses both your height and your weight to give one number. When you are still growing, the number must be plotted on a chart for your gender (female or male) with your age to see if you are inside or outside the healthy range. Your doctor or school should do this once a year as a check-up using the same chart to follow changes as you grow. BMI is a good indicator of healthy weight for height for someone your age.

To find your BMI, take your weight in pounds and divide it by your height in inches squared. Then, take this number and multiply it by 703. This is your BMI. For example, a 5-foot, 1-inch, 95-pound girl would have a BMI of 18, which is in the healthy range for a 10-year-old.

You can also go to a Web site and use an online BMI calculator to help you figure out your BMI. Once you click on the link, go to the second paragraph and click on the bold blue link that says "Children's BMI & Percentile Graph Calculator." Be sure to change the measurements to pounds and inches, if that's what you are used to using.

For adults, there are healthy ranges of BMIs, but for kids, it's a little more complicated, since their bodies are growing and not everyone's body grows at the same speed. The "healthy BMI range" for kids is between the 5th and 85th percentiles on a chart for boys and girls ages 2 to 20. Your doctor and school nurse have these charts. You also can download a copy of the chart for girls ages 2 to 20 yourself. Ask an adult to help you read and understand the chart if it is confusing to you. The Children's BMI & Percentile Graph Calculator listed in the paragraph above will tell you what percentile you are in after you calculate your BMI. See "It's Normal To Be Different" for information about adolescent height and BMI.

So, what do you do if your BMI is high? Talk to your parents, your doctor, or an adult you trust. They can help you figure out if you weigh too much for your height and suggest changes you may need to make in your life. Remember to balance a healthy diet with physical activity. A high BMI doesn't necessarily mean you are overweight. If you are very muscular, you may have a higher BMI than recommended for your age, weight, and height due to a higher proportion of lean body mass. And some people with more fat, less muscle, and small bones might have a BMI in the "healthy" range. That's why it's important to talk to your parents or doctor to see if your BMI is accurate for you.

Another way for your doctor to check if you're at a healthy weight is by measuring your percentage of body fat. There are a number of ways to do this, from using a tool to measure folds in your skin and comparing to a reference chart to putting you completely underwater. These are less common though, and chances are that your BMI is a pretty good indicator if you are following a healthy lifestyle.

1) American Academy of Pediatrics. "Prevention of Pediatric Overweight and Obesity," last referenced 7/6/04.

4Girls.gov: "You Are What You Eat: Body Mass Index Calculator"
KidsHealth: "What's the Right Weight for Me?"
KidsHealth: "How Can I Lose Weight Safely?"
Virginia Cooperative Extension: Knowledge for the CommonWealth. "Healthy Weights for Healthy Kids: What Is a Healthy Weight?"
Centers for Disease Control and Prevention's National Center for Health Statistics: "2000 CDC Growth Charts: United States"