A screening result is not a diagnosis, and the letter from your son's school comes out of a screening program: BMI screening programs are not intended to diagnose weight status. Schools that run them can refer students who need follow-up to local health care providers, and a letter like his can strongly encourage you to consult a medical care provider, such as his pediatrician or family doctor, who can examine him, to find out whether his weight presents a health risk.
How to read the percentile on the letter
The percentile measures one thing: where your son's BMI, a measure of weight relative to height, falls among boys of his age. Because children are still growing, a child's BMI has to be compared with children of his own sex and age, and the percentile shows how his compares with the BMIs of children in the reference population used to create the CDC growth charts. That population is the group whose measurements were used to create the charts, so the percentile compares him with that group, not with his classmates. A percentile gives the percent of the reference population a child equals or exceeds, so the 95th percentile on his letter means his BMI is the same as or higher than that of 95 percent of the boys his age in that group.
The category name on a letter comes from bands on those charts, which apply to children and teens 2 through 19:
| BMI-for-age percentile | Category |
|---|---|
| Less than the 5th | Underweight |
| 5th to less than the 85th | Healthy weight |
| 85th to less than the 95th | Overweight |
| 95th or greater | Obesity |
| 120% of the 95th or greater, or a BMI of 35 or greater | Severe obesity |
When his health is assessed, BMI is one possible health indicator, to be considered with other factors, which may include medical history, health behaviors, physical exam findings and laboratory findings.
The number also rests on two measurements taken at school, and height errors, in particular, reduce the validity of BMI. The preferred equipment for height is a stadiometer, a wall-mounted or portable unit made only for measuring height, and each measurement is best taken twice, with the student repositioned before each one. His doctor can measure him again and set the result beside any earlier readings in his chart.
Does a number in that band mean weight has to come off?
Not by itself. Whether weight needs to come off, or only to be put on more slowly while he grows taller, is for his doctor to decide, and the percentile is one input among several. In many cases, children who are overweight, the band just below his, do not need weight loss but slower weight gain as they continue to grow in height. Children grow at different rates, so it is not always easy to tell when a child has obesity or is overweight.
To decide whether a child weighs too much or is gaining weight too quickly, a health care professional considers many factors, such as:
- the child's age, weight, height and BMI-for-age percentile, the only item a school letter can supply
- the child's overall health
- how fast the child is growing
- any weight-related health problems, such as high blood pressure or high cholesterol
- the family's history of obesity and related health problems
You can gather the last item before the visit. Ask relatives which of them have had obesity or a related health problem, and tell his doctor what you learn.
Was he supposed to read the letter before you?
Not by being handed it. Under the safeguards CDC suggests for school BMI programs, results can be sent to parents by secure means, such as by mail, rather than brought home by students. To reduce the risk of stigmatizing students, letters can go to all parents, whatever the result, and a letter about a child who needs further evaluation can avoid definitive statements about his weight category, saying instead that the result "suggests" he "might be" overweight, so that it does not read as a diagnosis.
Older students may also be told their own result directly, but only where a school has every one of those safeguards in place, which include parental consent and private measuring, and only if staff keep it private and it does not stigmatize or label them. Under them, height and weight measurements must not be conducted within sight or hearing distance of other students, and only the staff member taking them should see the results.
Phone the school nurse or the other school-linked health care provider named on the letter, or the school office if it names no one. Ask what the school's policy on sharing results is and how this one reached your son, and ask for any later result to be mailed to you. Tell them he read it, because such letters could have a significant impact on students, and the school nurse or counselor can then be ready for reactions such as anxiety and despair. Tell them too if classmates saw or heard his numbers.
Should the school be measuring children at all?
There is no settled answer. When CDC last reviewed its school guidance, in 2022, there was not enough evidence for scientists to conclude whether school BMI programs are effective at preventing or reducing childhood obesity, or whether they cause harm, either by increasing the stigma attached to obesity or by increasing pressure to engage in unsafe weight control. That guidance made no recommendation for or against them.
Screening, the kind of program that sent his letter, exists to give parents information about their child's weight status. The other kind, surveillance, identifies the percentage of students who are underweight, healthy weight, overweight or obese; its data are typically anonymous, and it is not meant to tell parents about their own child.
How to keep him out of the next measuring
Under the safeguards CDC suggests for school programs, parents must be given the option of declining permission to measure their child's BMI, so ask the school whether, and how, you can decline in your district. Some programs use passive consent, in which every student is measured unless a parent sends a written refusal. A district can instead require active consent, in which only students who signed a consent form, and whose parents also signed one, are screened. Under passive consent, a written refusal sent before the next round of measuring is how he is left out of it.
What a doctor's appointment can do with the result
His doctor can examine him, which the school's measurement cannot do. A student classified as overweight or obese after screening requires further medical examination to determine whether he in fact has excess body fat or other conditions related to obesity, such as diabetes or prediabetes, high blood cholesterol or triglyceride levels, or early pubertal maturation. Take the letter with you, and ask his doctor to check whether his weight and height are in a healthy range.
Any plan for him starts at that appointment: do not put him on a weight-loss plan without the help of a health care professional, who may recommend a plan tailored to his needs or refer you to a weight-management specialist or a registered dietitian. A local hospital, a community health clinic or the health department may offer weight-management programs for children and teens. If a weight-loss program is necessary, involve the whole family in healthy habits, so that he does not feel singled out.
For an older child, the options go beyond habits. If he is 12 or older and has obesity, you can ask his doctor about other treatment options, such as weight-management medicines for children 12 and older, or weight-loss surgery for teens 13 and older, the kind known as bariatric and metabolic surgery. Neither replaces changes to eating and activity, and both work best when a child is physically active and consumes healthy foods and beverages (see Your teenager asked about a weight medicine. It is a question for her doctor).
NicoCares cannot take on his care, because anyone using NicoCares must be 18 or older and may use it only for themselves; his weight is a matter for his own pediatrician or family doctor.
Signs to watch for in him after the letter
Watch for signs that he has started trying to control his weight in unsafe ways, since pressure toward unsafe weight control is one of the possible harms of these programs. Signs that he may benefit from an evaluation include dieting or exercising excessively or fearing gaining weight, spending more and more time alone, and losing interest in things he used to enjoy. If what you see lasts for weeks or longer, upsets him or the family, or gets in the way of school, home or friends, describe it to his pediatrician, who can refer him to a mental health professional with experience in evaluating and treating children.
Ask him whether anyone at school has said anything about his weight or the letter, because weight-related teasing or bullying can affect a child's mental health. How children feel about themselves is often based on how they think their parents feel about them, so talk with him about health, and tell him he is loved, special and important.
If he talks about wanting to hurt himself or someone else, or his behavior is unsafe, seek help immediately: text or phone 988, the Suicide & Crisis Lifeline. If anyone's life is in danger, call 911.
