Dr. Robert Needlman
Specialist in pediatric behavior and development.
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 Ask Dr. Needlman
Worried Friends Are Underweight | | | QUESTION | | | Dear Dr. Needlman,
My friend is 97lbs and 5'5" - is she under weight? Also, my other friend Tina is 4'10' and 78lbs - is she under weight? Both are 13.— Worried Friend in NY | | | ANSWER |
April 6, 2001 | | | Dear Worried Friend,
This question is actually more difficult than you might think. Certainly, both of your friends are thin, but it's harder to say whether their weight is healthy, or a sign of a problem. In thinking about weight for any teenager, there are some things to keep in mind:- What is their growth pattern over time? A person who has always been on the thin side may be normally thin. If a person's weight has fallen off in the last few weeks or months, there's probably another reason, possibly a medical or psychological problem.
- What is their family's body build? A very thin person who comes from a family of thin people may just be following the family genetic pattern. If a person's body is very different in shape from the other people in their family, the reason is less likely to be genetics.
- How is their general health? An active, mostly up-beat, healthy person who is thin is likely to be just healthy and thin. A thin person who is tired all the time, sad, or withdrawn is more likely to have something else going on (depression, for example, which is very common in teens).
- How accurate were the measurements? Different scales can be off by quite a bit, and it's easy to add or lose several inches in height, depending on how, exactly, you take the measurements. Doctors and nurses are trained in measuring and weighing bodies, so if there is a question about weight, it's best to get the measurements from the doctor.
Once you have accurate measurements, you can use something called the Body Mass Index, or BMI, to find out it the person is underweight or overweight. First, go to the Body Mass Index web-page. Read the explanation, and then click on the "Body Mass Index Web Calculator." Enter the measurements, and then read off the BMI number. Use the "back" button to get back to the first BMI page, and then follow the directions under "Using the CDC Growth Chart to Plot BMI for Age." All this sounds complicated, and it will take some patience on your part.
I went through this process with the numbers you gave me for your friends, and indeed they both come out quite low--lower than 97 out of 100 13-year-old girls. But the meaning of that depends on all of the considerations above. Of course, your friends can also ask their doctors about their weight. The doctor will have accurate measurements, do all the work of plotting the weights, and know how to determine whether or not there is a problem.— by Robert Needlman, M.D., F.A.A.P. |
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