Is a child's neck size a better way to gauge childhood obesity than body mass index (BMI)?

Answers from Jay L. Hoecker, M.D.

Measuring a child's neck size is a relatively new method of screening for childhood obesity that's accurate and easier to obtain than BMI. Although the technique isn't routinely used yet and further research is needed, early studies suggest that neck size is another tool that can be used to identify overweight and obesity in boys and girls ages 6 to 18.

BMI is calculated by taking a child's weight in kilograms and dividing it by a child's height in meters squared. The doctor calculates your child's body mass index (BMI) and determines where it falls on a standard BMI-for-age growth chart. BMI helps indicate if your child is overweight for his or her age and height. BMI, however, doesn't consider factors such as being muscular or having a larger than average body frame and the variation in growth patterns among children. As a result, the doctor must also consider your child's growth and development to determine whether your child's weight is a health concern.

Unlike BMI, measuring a child's neck size to identify obesity is straightforward — the doctor simply places measuring tape around the most prominent part of your child's neck and compares the measurement to values that indicate overweight and obesity for your child's age. Neck size also is a better gauge of upper body fat than is BMI. That's important because upper body fat can help predict certain obesity-related complications, such as high blood pressure, diabetes, heart disease and obstructive sleep apnea.

If you're interested in having your child's neck size measured or you're concerned about your child's weight, consult your child's doctor.

Nov. 02, 2010 See more Expert Answers