Study: 80 percent of U.S. teens have an unhealthy diet OKLAHOMA CITY, April 7 (UPI) -- More than 80 percent of U.S. teens have a poor diet and many are not physically active, U.S. researchers say. Lead author Christina M. Shay of the College of Public Health at the University of Oklahoma Health Sciences Center in Oklahoma City said the study involved 4,673 adolescents ages 12-19 that represented about 33.2 million adolescents nationally. The researchers estimated the current state of cardiovascular health of U.S. adolescents based on the seven cardiovascular health components: blood pressure, total cholesterol, body mass index, blood glucose, healthy diet, physical activity and smoking. The healthy diet score was based on levels of fruits and vegetables, fish, whole-grains, salt and sugar-sweetened beverage intake recommended by the American Heart Association. It was the least favorable measure for both boys and girls across ethnic groups. The study, published in the journal Circulation, also found fewer than 50 percent of the adolescents had five or more acceptable levels of the health factors --- 45 percent of boys and 50 percent of girls -- and fewer than 1 percent of boys and girls reached ideal healthy diet levels. Forty-four percent of the girls and 67 percent of the boys reached ideal physical activity levels. Two-thirds of adolescents had ideal BMI levels, but one-third of adolescents had total cholesterol levels in intermediate or poor ranges. One encouraging finding was the majority of boys and girls had never smoked a cigarette or hadn't tried to smoke one within the previous 30 days of two interviews during the five-year study, the researchers said.