A child's waistline is the best predictor, in terms of body measurements, of his or her risk for heart disease later in life, according to a new study. Waist size was even better at predicting heart disease risk than the commonly used measure of body mass index, or BMI, a ratio of height to weight.

Boys with large waists were 5 times more likely, and girls 6 times more likely, to develop metabolic syndrome as young adults than those with smaller waists. Metabolic syndrome is a collection of symptoms associated with cardiovascular disease , including high blood sugar, high blood pressure and low levels of "good" cholesterol. The syndrome has been implicated in an increased risk of stroke, coronary artery disease and Type 2 diabetes.

In contrast, boys with high BMIs were 3 times more likely to develop metabolic syndrome than those with low BMI's. For girls, high BMI increased the risk 5-fold.

"High body mass index is still is a decent marker for long term risk, but it wasn't as good as waist circumference," said study researcher Michael Schmidt, of the University of Georgia.

The results suggest waist size "would be a good measurement to use in clinical settings if we want to identify those children who are most at risk for future health complications," he said.

The study is one of the first to compare different body measurements and how well they predicted future disease risk.

While BMI is easy to calculate, it doesn't distinguish between body mass composed of fat and mass composed of muscle, the researchers said. It also doesn't take into account where the fat is stored. Previous studies have found that visceral fat, or belly fat, has more adverse health effects than does fat stored in other areas .

Waist circumference may be a superior predictor because it provides an indication of the amount of fat stored centrally in the body, Schmidt said.
The researchers analyzed data from 2,188 Australians who took part in a health and fitness survey in 1985, when they were ages 7 to 9. These children were followed up about 20 years later, between 2004 and 2006.

The results provide a more contemporary view of the risks associated with childhood obesity , Schmidt said. Many earlier studies used data from surveys of children in the 1950s, 60s and 70s, when fewer children were obese or severely obese , Schmidt said.

The study is published in the Sept. 28 issue of the journal International Journal of Obesity.