Waist circumference and physical activity, in addition to body mass index (BMI), play an important role in cardiovascular and diabetes risk factors in children, according to researchers at the USDA Agriculture Research Service Children's Nutrition Research Center at Baylor College of Medicine and Texas Children's Hospital in a study that appears in the current issue of Metabolic Syndrome and Related Disorders.
"We should consider screening children for waist circumference since it seems to be related to children's metabolic risk, above and beyond BMI," said Dr. Jason Mendoza, assistant professor of pediatrics – nutrition at BCM and first author of the paper.
The study was conducted using nationally representative data on children between the ages of 6 to 19 years from the National Health and Nutrition Examination Survey, 2003-2004 and 2005-2006.
Group of risk factors
Metabolic syndrome refers to a group of risk factors that lead to increased risk of heart disease, stroke and type 2 diabetes. Researchers looked at traditional metabolic syndrome risk factors, including blood pressure, HDL and LDL cholesterol, triglycerides, glucose and insulin.
They found that waist circumference, which is a measure of abdominal fat, was more strongly related to risk factors than BMI, which is a measure of overall body fat based on height and weight.
"Those with a higher waist circumference had a worse metabolic profile than those with a high BMI," said Mendoza.
Higher waist circumference was associated with lower HDL cholesterol (good cholesterol) and higher C-reactive protein, glycohemoglobin, fasting triglycerides and fasting insulin – all risk factors for metabolic syndrome.
BMI still useful measure
Mendoza emphasizes that BMI is still a useful measure of obesity and health. If confirmed by other studies, screening for waist circumference should take place in addition to BMI. He also recommends developing national standards for healthy and unhealthy waist circumference.
Researchers also found that more moderate to vigorous physical activity, strenuous activity that children should be getting at least 60 minutes each day, was associated with lower blood pressure and higher HDL cholesterol (the good cholesterol).
Because physical activity is also strongly related to the risk factors, Mendoza suggests developing practical and easy ways to screen for physical activity.
Physical activity important
"We found that regardless of BMI and waist circumference, physical activity was associated with a healthier metabolic profile," said Mendoza.
There are several new tools that could aid in measuring physical activity, including accelerometers and smart phone applications, said Mendoza.
Others who took part in this study include Dr. Theresa A. Nicklas, Yan Liu, Dr. Janice Stuff and Dr. Tom Baranowski, all with BCM.
Funding for this study came from the National Cancer Institute and the U.S. Department of Agriculture.