"What's the right weight for my height?" is one of the most common questions girls
and guys have. It seems like a simple question. But for teens, it's not always an
easy one to answer. Not everyone grows and develops on the same schedule.
It's normal for two people who are the same height and age to have very
different weights. First, not everyone goes through puberty
at the same time. Some kids start developing as early as age 8 and others might not
develop until age 14. During puberty, the body begins making hormones
that spark physical changes like faster muscle growth (particularly in guys), spurts
in height, and weight gain. Second, people have different body types. For example,
some are muscular and large framed while others are thinner with smaller frames.
For these reasons, you can't point to a number on a scale as the "right" number.
But it is possible to find out if you are in a healthy weight range for your height
and age. That's why doctors use body
mass index, or BMI.
Figuring Out BMI
Because weight gain is more complicated during our teens, doctors don't rely on
weight alone to figure out if someone is in a healthy weight range. Instead, they
use BMI. BMI helps doctors estimate how much body fat a person has based on
his or her weight and height.
The BMI formula uses height and weight measurements to calculate a BMI number.
This number is then plotted on a BMI chart, which has lines called percentiles. BMI
percentiles show how a teen's measurements compare with others the same gender and
age. For example, if a teen has a BMI in the 60th percentile, 60% of teens the same
gender and age had a lower BMI.
The categories that describe a person's weight are:
Underweight: BMI is below the 5th percentile for age, gender,
Healthy weight: BMI is equal to or greater than the 5th percentile
and less than the 85th percentile for age, gender, and height.
BMI is at or above the 85th percentile but less than the 95th percentile for age,
gender, and height.
Obese: BMI is at or above the 95th percentile for age, gender,
It's important to look at the BMI numbers as a trend instead of focusing on individual
numbers. Any one measurement, taken out of context, can give you the wrong impression
of your growth.
What Does BMI Tell Us?
You can calculate BMI on your own, but it's a good idea to ask your doctor, school
nurse, or other health professional to help you figure out what it means.
BMI is not a direct measure of body fat, and it doesn't always tell the
full story. People can have a high BMI because they have a lot of muscle
(like a bodybuilder or athlete) instead of excess fat. Likewise, a person with a small
frame might have a normal BMI but could still have too much body fat.
How Can I Be Sure I'm Not Overweight or Underweight?
If you think you've gained too much weight or are too skinny, a doctor can help
you know if it's normal for you or whether you do have a weight problem. At each visit,
your doctor measures your height and weight and plots your BMI. He or she uses those
measurements over time to tell whether you're growing as expected.
If your doctor is concerned about your height, weight, or BMI, they may ask questions
about your health, physical activity, and eating habits. Your doctor also may ask
about your family background to find out if being tall, short, or a late bloomer (someone
who develops later than other people the same age) runs in your family. The doctor
can then put all this information together to decide whether you might have a weight
or growth problem.
If your doctor thinks you're overweight, he or she may refer you to a dietitian
or doctor specializing in weight management. These experts can offer eating
and exercise recommendations based on your individual needs. Following a doctor's
or dietitian's plan that's designed especially for you will work way better than following
What if you're worried about being too skinny? Most teens who weigh less
than other people their age are healthy. People in your family may be small
or thin, or you might be going through puberty later than some of your peers, or your
body may be growing at a slower rate. Most underweight teens catch up and there's
rarely a need to try to gain weight.
Sometimes, teens may be underweight because of a health problem that needs treatment.
See a doctor if you notice any of these things:
You feel tired or ill a lot.
You have a cough, diarrhea, poor appetite, or other problems that have lasted
for 2 weeks or more.
You are losing weight.
Some people may be underweight because of an eating
disorders, like anorexia or bulimia. Talk to your doctor if you think you may
have an eating disorder.
Getting Into Your Genes
Heredity plays a role in body shape and what a person weighs.
Body shape and weight tends to run in families. So family members may have similar:
body types: they have fat in certain parts of their bodies
body composition: their amounts of bone and muscle versus fat
the only things that family members may share. Eating and physical activity habits
can be passed down too. If your family eats a lot of high-fat foods or snacks or doesn't
get much exercise, you may do the same.
But genes are not destiny. The good news is these habits can be changed for the
better. Even simple changes like walking more or taking the stairs can benefit a person's
health. No matter what genes you inherit, you can be healthy and be the weight that's
right for you eating a balanced
diet and being active