Obesity in Children (cont.)

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Medical Author:

Robert Ferry Jr., MD

Robert Ferry Jr., MD, is a U.S. board-certified Pediatric Endocrinologist. After taking his baccalaureate degree from Yale College, receiving his doctoral degree and residency training in pediatrics at University of Texas Health Science Center at San Antonio (UTHSCSA), he completed fellowship training in pediatric endocrinology at The Children's Hospital of Philadelphia.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Exams and Tests

Weight-to-height tables

These tables give general ranges of healthy weights and overweight for a child's height. Many health care providers define obesity in a child as weighing 20% or more over the healthy range. The tables, however, do not take into account the individual characteristics of each child. The healthcare provider must consider the child's age and growth pattern when interpreting the chart. For example, some children gain weight before a growth spurt. This doesn't mean they are becoming obese.

Body fat percentage

The percentage of body weight that is fat is a good marker of obesity. Boys over 25% fat and girls over 32% fat are considered obese.

Body fat percentage is difficult to measure accurately, however. The most accurate methods use special equipment that is not found at most medical offices. The method that measures skinfold thickness is not reliable unless it is done correctly by a trained and experienced technician.

Body mass index (BMI)

This measure is used to assess weight relative to height. It is the same as the body mass index used to identify adult obesity. BMI is defined as weight in kilograms divided by height in meters squared (kg/m ²). BMI also can be calculated in pounds and inches. BMI is closely related to body fat percentage but is much easier to measure.

BMI is the standard for defining obesity in adults, but its use in children is not accepted universally. The Centers for Disease Control and Prevention(CDC) suggests two levels of concern for children based on the BMI-for-age charts.

At the 85th percentile and above, children are "at risk for overweight" and,

At the 95th percentile or above, they are "overweight".

The American Obesity Association defines those children above the 95th percentile as "obese", which corresponds to a BMI of 30 (considered obese in adults).

To calculate a child's body mass index, follow these steps:

Multiply the child's weight in pounds by 705
Then divide by the child's height in inches
Divide this by the height in inches again

To calculate body mass index on the Internet, fill in the child's height and weight at the Web site of the Department of Health and Human Services, Obesity Education Initiative.

Waist circumference (WC)

This measurement in a child or adolescent correlates closely with the future risk of developing type 2 diabetes mellitus and related complications of the a href="/script/main/art.asp?articlekey=103831">metabolic syndrome (high blood pressure, abnormal circulating cholesterol or other fat levels, heart attack, stroke, and damage to eyes, heart, and kidneys). The assessment is made with a tape measure stretched across the widest abdominal girth (usually at or just below the level of the belly button, called the umbilicus). Any value over the 90th percentile for age and gender carries the highest risk.