Please note: This information was current at the time of publication. But medical information is always changing, and some information given here may be out of date. For regularly updated information on a variety of health topics, please visit, the AAFP patient education website.

Information from Your Family Doctor

Failure to Thrive: Why Is My Child Underweight?


Am Fam Physician. 2003 Sep 1;68(5):886.

What is failure to thrive (FTT)?

Failure to thrive (FTT) is a growth problem in children, especially those younger than two years. A child who fails to thrive is behind in physical growth or size or doesn't gain enough weight. There are many possible causes of FTT, such as poor appetite, poor diet, or a medical problem. Young children need a lot of calories to grow. FTT can happen even if a child seems to be eating enough.

How can my doctor tell if my child has FTT?

Your doctor will weigh and measure your child regularly. These measurements are put on a growth chart. If your child's growth starts to slow down, the doctor will want to check your child more often to be able to diagnose FTT.

How is FTT treated?

FTT is treated two ways. The first way is to treat the problem that is causing your child to be underweight. The second way is to increase the number of calories your child is eating. Infants who are breastfed can be given extra formula with breast milk. Bottle-fed babies may need to have their amount of formula increased, or the formula may need to be prepared in a special way. Calorie boosters are high-calorie foods such as cheese, peanut butter, regular milk, and cooking oils. These boosters can be added to the food your child usually eats, such as mashed potatoes, noodles, or crackers. Your doctor may recommend using a high-calorie milk drink or giving your child extra vitamins. Talk to your doctor about what foods are right for your child.

If your doctor decides your child is getting enough calories but is still not gaining weight, tests can be done to look for medical problems that can cause poor growth.

How can I prevent FTT?

Feeding children can be hard. If you or your child often gets frustrated at meal times, talk with your doctor about ways to help your child eat better. Children eat best when the whole family is together and the stress level is low.

Where can I find more information?

To see a growth chart, go online to:, or ask your doctor for a copy.

The American Academy of Family Physicians has a Web site ( that offers nutrition information and other healthy living advice.

Be careful about using the Internet or quick fix diet books for children. There are many good Web sites and books about childhood nutrition, but there are also some that advertise products or give advice that are not based on good medicine. Ask your doctor about any nutrition advice you have read about or found on the Internet.

This handout is provided to you by your family doctor and the American Academy of Family Physicians. Other health-related information is available from the AAFP online at

This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.


Copyright © 2003 by the American Academy of Family Physicians.
This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. Contact for copyright questions and/or permission requests.

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