A new study shows that Arkansas schools have a greater proportion of junk food in their vending machines than does the average U.S. school. Nationally, 75 percent of drinks and 85 percent of snacks lack nutritional value. The study by the University of Arkansas for Medical Sciences shows vending machines in Arkansas schools spew out even more junk. In Arkansas, 80 percent of drinks and 86 percent of snacks were of poor nutritional quality. Obesity among Arkansas students has been drawing national attention -- but part of the reason is that the state is trying to address the problem. Public school students are taking home body mass index reports, part of a state effort to combat obesity among the young. The national survey by the Center for Science in the Public Interest examined the contents of more than 1,400 vending machines in 251 schools in 23 states.