According to a recent study conducted in U.S. schools and announced on Friday, French fries and other fatty and sugary foods and drinks are becoming harder to come by, but many schools are falling short on providing physical education for pupils.

More schools prohibit smoking and other tobacco use, but more than a third do not have such a ban, according to the report from the U.S. Centers for Disease Control and Prevention.

The report tracked school health policy changes from 2000 to 2006. Janet Collins, who heads the CDC's National Center for Chronic Disease Prevention and Health Promotion, said it showed encouraging progress but more work needs to be done.

Many experts have pointed to the abundance of junk food in elementary, middle and high school cafeterias and vending machines as a factor in the rise in U.S. childhood obesity.

The CDC report showed that some, but certainly not all, of this stuff may be disappearing from schools.

For example, Howell Wechsler, director of CDC's Division of Adolescent and School Health, said 19 percent of schools sold French fries in 2006, compared to 40 percent in 2000.

"That means that approximately 25,000 more schools have stopped serving deep-fried potatoes. That's about equivalent to all of the schools in California, New York, Texas and Florida combined," Wechsler said.

The report also found that more schools are offering salads, low-fat or non-fat yogurt, and low-fat salty snacks like pretzels and baked chips. Fewer were selling cookies, cake or other high-fat baked goods in vending machines, it found.