If you glance at any class photo, you might notice that most kids don't have the exact same body type. Girls come in a wide variety of healthy shapes and sizes. Even among girls who have the same body type, not all girls develop at the same pace. However, your doctor might use a growth chart to determine whether your weight and height are above or below the national average for girls in your age range. This will give him some insight, but it isn't the only factor that determines your health.
To accurately find the average weight and height for girls you will need to find the most recent data available. The average height and weight of Americans has changed over time. For example, in 1963 the average height for 10-year-old girls was approximately 55½ inches and the average weight was about 77 lbs. By 2002, the average height of 10-year-old girls was over 56 inches and the average weight was almost 88 lbs.
Body Mass Index
Weight and height don't tell the full story about your health. That is why your doctor might use body mass index, or BMI, to estimate your body fatness based on how your weight correlates to your height. Doctors calculate BMI by dividing a person's weight in pounds by her height in inches squared and then multiply the product of that equation by the number 703. The resulting number might be somewhere between 15 and 30. When you're a child, you grow at such a fast pace that a BMI number by itself doesn't say whether you are a healthy weight or height. Where your BMI ranks on a growth chart matters more.
You are in the underweight category if your BMI is under the 5th percentile for all girls your age, in the healthy weight category if it is at the 5th but under the 85th percentile and overweight or obese if your BMI is at or over the 85th percentile. According to BMI growth charts published in 2000 by the Centers for Disease Control and Prevention, a 9-year-old girl would be in the 50th percentile if her BMI were 16.30 and a girl of 12 and a half would be in the 50th percentile if her BMI were 18.42.
Girls tend to get taller at a steady pace of about 2.5 inches per year. Your weight will increase at a faster pace starting at about age eight or nine and you will experience more dramatic changes as you enter puberty, when your body's proportions of fat, bone and muscle change. However, since girls don't all develop at the same time you may find that you weigh a lot more or less than a friend who is the same age and height as you. This is normal.
A major factor that influences your weight and height is your genes. Chances are you will be on the tall side if you have tall parents and you will be on the shorter side if you have shorter parents. If your parents think you aren't growing at a healthy pace they may take you to see your doctor, who can test you for medical conditions such as hormone deficiencies. Your doctor may also suggest that you are underweight or overweight due to lifestyle factors such as poor diet. If this is the case, he will suggest making some healthy changes based on your specific needs.
- The Nemours Foundation: What's the Right Weight for My Height?
- The Centers for Disease Control and Prevention: About BMI for Children
- The Centers for Disease Control and Prevention: Body Mass Index for Age Tables, 2000
- The Nemours Foundation: Growth and Your Six to 12-Year-Old
- The Centers for Disease Control and Prevention: Americans Slightly Taller, Much Heavier Than Four Decades Ago