By Keyana Washington, MD, MPH
When your teen comes to the office for a check up, the nurse will check the vital signs: temperature, heart rate, blood pressure, respiratory rate. These are important markers of your child’s general health and well being. These days, there is another equally important marker of health: the body mass index.
The body mass index (BMI) is a calculation used to compare your teen’s weight to his/her height. Medically, it gives us a rough estimate of percent body fat and is used to determine whether your teen is underweight, healthy weight, overweight, obese or severely obese. When combined with family history, diet and exercise history, BMI can be used to predict risk for diseases such as diabetes, high cholesterol, and hypertension.
During the discussion of your teen’s BMI, you may hear us refer to “percentiles”. In adults, the BMI number alone is used to determine whether or not a person is of healthy weight. In children and teens, however, we use the percentiles to make this determination. 5th to 85th percentile is the range for healthy weight. A teen that in the 5th percentile is underweight. 85th to 95th percentile is overweight, 95th to 99th percentile is obese and greater than 99th percentile is severely obese.
Many families prefer not to use the terms “overweight” or “obese” because they fear the negative emotions that have been associated with this term in the media. However, it is important to realize that these are medical terms, just like “diabetic” or “asthmatic”, and are not intended to be used as negative labels. Rather, they are used to describe one aspect of your teen’s health and determine the level of intervention that is needed to make improvements in their health.
It is important to know your teen’s BMI and to ask your doctor whether their BMI is in a healthy range. Studies have shown that a BMI higher than the 85th percentile puts teens at increased risk of developing high cholesterol, type 2 diabetes, high blood pressure, heart attack and stroke as an adult. This is especially true if there is a family history of these diseases. In addition, teens with a high BMI are more likely to be alienated by their peers and experience depression or anxiety.
If your teen’s BMI is greater than 85th percentile, talk to your doctor. Together with you and your teen, we can develop a plan to move their BMI to a healthy range. This will include plans for eating a healthy diet, increasing exercise and may include labwork, referral to a nutrition expert and/or referral to a structured weight loss program. Check out these websites for more information on BMI, diet and exercise: