That's the equivalent of one McDonald's hamburger, a large fries at Wendy's, or a medium chocolate-dipped cone at Dairy Queen - every single day.
That percentage is only slightly less than the last time this number was measured in 2006, when kids got an all time high of 13% of their calories from fast food, according to a new report from the CDC's National Center for Health Statistics.
These numbers come from the 2011-12 National Health and Nutrition Examination Survey.
Adolescents especially consumed more calories from on-the-go foods than children: of those ages 12-19, about 17% of their daily calories came from fast food. In comparison, children ages 2-11 got 8.7% of their daily calories from the same kinds of food.
In its report, the NCHS notes that fast food consumption has been linked to higher caloric intake and poorer nutrition habits in children and adolescents. It's also been linked to weight gain in adults.
All this doesn't look good for a country where the obesity rate in children has doubled in the past 30 years, and quadrupled in adolescents. As of 2012, about 18% of children and 21% of adolescents are considered obese, according to the CDC. Obese kids are more likely to be at risk for high cholesterol, high blood pressure, and developing diabetes.