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Healthy Weight Ranges And BMI

What is BMI?

BMI stands for Body Mass Index. BMI does not measure body fat directly, but is a reliable indicator of body fatness for children, teens, and adults. A person’s calculated BMI can give a good indication of whether that person is underweight, in a healthy weight range, or overweight. For children and teens, BMI is age and gender-specific in a way it is not for adults. This is because the amount of body fat changes with age and the amount of body fat differs between girls and boys during childhood and adolescence.

BMI can be calculated for children, teens and adults – but since we are a teen website we will only be talking about teens here. Teens can calculate their BMI using their weight and height measurements using a BMI Percentile Calculator for Child and Teen.

What is a BMI percentile?

After BMI is calculated for teens, the BMI number is plotted on a chart appropriate for that teen’s exact age and gender to get a percentile ranking. The percentile ranking indicates the position of that teen’s BMI number among adolescents of the same sex and age.

Weight Status Category

Percentile Range


Less than the 5th percentile

Healthy weight:

5th percentile to less than the 85th percentile


85th to less than the 95th percentile


Equal to or greater than the 95th percentile


What this means is that if you calculate your BMI and find out you are in the 40th percentile, it means that you are in a healthy weight range and that your weight is greater than 40% of teens of the same age and gender.

Why is BMI used?

BMI is usually used as a screening tool to help identify teens with weight problems. By calculating a teen’s BMI, a teen, parent, or healthy professional can get an idea if a teen is underweight, in a healthy weight range, overweight, or obese. It can also be used to determine if a teen is at risk for developing a weight problem. If a teen measures at the 84th percentile, that teen would technically fall into the healthy weight range – but it would be important for some further evaluation to occur to determine how at-risk this teen is for becoming overweight. By assessing people’s risk for being overweight or obese, BMI can also help identify risk of developing medical conditions such as high cholesterol, high blood pressure, and diabetes.  

Can BMI be used to diagnose someone as underweight or obese?

No. BMI is a very useful screening tool, but is not something used to give a final diagnosis. If you calculate your BMI and are concerned about the percentile range in which you fall, it is important to follow up with your primary care physician or adolescent medicine specialist. A full physical would help a medical professional make a determination about any weight problems. A full assessment would also help a medical professional to outline changes that need to made in regards to diet, health, and physical activity so that you can maintain your weight in a healthy range.  

What do I do if my BMI percentile places me outside of healthy weight range?

If your BMI indicates that you could be underweight, overweight, or obese, it is strongly recommended that you follow up with your primary care physician or an adolescent medicine specialist. BMI calculations and results are not 100% perfect, so it is important for a medical health professional to verify whether or not you are underweight, overweight, or obese, as well as to determine the possible causes in the event that you are. Teens, for example, can gain weight quickly, and subsequently have their BMI go up, as a result of going through puberty. So changes in BMI may be a normal part of development or something that requires more looking into – so it is important to consult with a doctor and not let the BMI calculation be the final word.  

Some people are underweight or overweight because of medical problems that require treatment from a medical health professional. Others experience problems with their weight because of mental health problems. Some people are underweight because they are anorexic. Some people are overweight because they are dealing with a depressive disorder and eat excessively as a way to self-soothe. If your doctor has concerns about your weight and feels emotion issues may be contributing to a weight problem, you would most likely benefit from meeting with a mental health professional trained in working with people with various types of eating disorders. Remember that eating disorder doesn’t just mean people who are anorexic or bulimic and who are underweight. People with eating disorders such as binge eating disorder are overweight or obese.

What can I do to stay in a healthy weight range?

There are health risks associated with being underweight, as well as with being overweight or obese. So it is important to adopt healthy lifestyle habits when it comes to diet and physical activity.

·         Don’t skip meals. Eat three meals a day and one or two healthy snacks.

·         Replace junk foods in your house with healthy meal and snack-food items, especially fruits, vegetables and whole grains.

·         Limit high-calorie foods, including sugary drinks, fast foods, and packaged snacks.

·         Remember portion control.

·         Keep food choices varied. Include foods from all the food groups, including a reasonable amount of healthy fats in your diet.

·         Exercise at least three times a week.

·         Don’t over-exercise.

·         Try to cut down on “couch potato” time.

·         Ask your friends and family members to join you in living a healthy lifestyle.  

·         Establish regular family mealtimes.



·         If you don't have a doctor and live in northern New Jersey, you can call the Adolescent/Young Adult Center for Health at 973-971-6475 for an appointment or contact your local teen health center or Planned Parenthood. You can also contact your insurance company for a list of in-network providers.

·         If you live in northern New Jersey, contact Kid-FIT, a health management program at Morristown Memorial Hospital for people 6-21 years of age. 973-971-8824,

·         If you live in northern New Jersey and need help finding a therapist you can call the Access Center from Atlantic Behavioral Health at 888-247-1400. Outside of this area you can log onto the US Department of Health and Human Services Substance Abuse and Mental Health Services Administration website for referrals in your area. You can also contact your insurance company to get a list of in-network mental health providers or check with your school social worker or psychologist to get a list of referrals in your area.

·         If you live in New Jersey, you can contact the Eating Disorders Program at Atlantic Health at 908-522-5757 for more information and to set up an evaluation. Outside of New Jersey you can contact the National Eating Disorders Association at 1-800-931-2237 for more information and referral services.