Measuring the width of a child's neck could be a quick and easy way to flag a child as potentially overweight, according to new research.
It could become a useful tool for both parents and doctors to get a fast gauge of a child's possible body fat, said Olubukola Nafiu, a pediatric anesthesiologist at the University of Michigan medical school who led the study.
In a study of more than 1,000 children ages six to 18, Dr. Nafiu found a high correlation between bigger neck measures, high Body Mass Index (BMI) and waist measurements.
This suggests that one day doctors could skip BMI calculations, which are determined by dividing a person's weight in kilograms by the square of their height in metres, which some consider an imperfect indicator.
Based on neck measurements, doctors could move immediately to more accurate techniques used to diagnose obesity, such as skin-fold thickness measurements, evaluations of diet and physical activity and family history.
The research found that a six-year-old boy with a neck circumference of more than 28.5 centimetres would be considered at risk of being overweight. For a six-year-old girl the cutoff is 27 centimetres.
By age 18, the cutoffs would be 39 cm and 34.6 cm, respectively. The measurements were done with a flexible tape measure at the thyroid cartilage, also known as the Adam's Apple.
Measuring the neck could be a more practical tool than either the BMI or waist measurements for both the doctor and the child, says Dr. Nafiu. For one thing, it can be hard to gather both height and weight properly in busy medical settings.
And neck measurements don't require kids to remove clothing or be subjected to a doctor putting his arms around them to take a waist measurement.
It might also be a less abstract warning to parents.
"For years we've been using BMI and it hasn't really made a big dent on the prevalence of overweight and obesity in children," he says. "If you tell parents 'your child's neck is this wide, these are some of the problems associated with a wide neck.' These are things people can relate to."
As a pediatric anesthesiologist, Dr. Nafiu is especially interested in the way obesity can complicate surgery. A wider neck may constrict the airway and contribute to lower oxygen levels, for instance.
Canadian obesity expert David Lau, a professor of medicine at the University of Calgary, says Dr. Nafiu's study is a good step toward understanding how neck circumference could work as a screening tool.
"There's no question that neck circumference is a pretty good measure for body fat distribution, because the bigger the neck, the bigger the waistline," says Dr. Lau, a professor of medicine at the University of Calgary.