"As we gear up to take on this epidemic of obesity, we cannot abandon protecting our children from secondhand smoke and smoking," said lead author Michael Weitzman, executive director of the American Academy of Pediatrics Center for Child Health Research in Rochester, N.Y.

For the study, metabolic syndrome was defined as having at least three of five characteristics: a big waist, high blood pressure, high levels of blood fats called triglycerides, low levels of good cholesterol, and evidence of insulin resistance, in which the body cannot efficiently use insulin.

In the study, published yesterday in the American Heart Association online journal Circulation, researchers found that 6 percent of 12-to-19-year-olds had the syndrome and that the prevalence increased with exposure to tobacco smoke.

The study found that 1 percent of those unexposed to smoke developed the syndrome, 5 percent of those exposed to secondhand smoke had the disorder, and 9 percent of active smokers had it.

When researchers looked at teens who were overweight or at risk of being overweight, the effect was even more marked, with 6 percent of those not exposed to smoke developing syndrome, 20 percent of those exposed to secondhand smoke getting it, and 24 percent of smokers suffering from the disorder.