By Marciene Mattleman

PHILADELPHIA (CBS) – Findings from a national study show that fast food not only increases kids’ weight but decreases test scores.

Data from a group of 1700 children in research from Ohio State University, measured how much fast food the kids were eating at age 10 and compared consumption levels with test results in reading, math and science three years later.

Those who ate fast food daily performed 20% lower than those who did not. Even small increases in eating fast food increased the frequency with which students who ate fast food were associated with poorer test results.

While the study observed children in 2004, an article in The Washington Post suggests there’s no reason to believe that much has changed. In 2008, almost one third of American kids, ages 2-12 and almost half of those 12-19 ate or drank something from a fast food restaurant every day. Not a good sign.