LITTLE ROCK, Arkansas (AP) — Arkansas schoolchildren appear to be holding their own in the battle against bulge.

Body mass indices released Monday in the nation's first state to track the numbers showed 20.6 percent of schoolchildren tested last school year were overweight and 17.2 percent were at risk for being overweight. That's about the same as the year before.

State officials were optimistic but urged diligence.

"We've got to keep everybody engaged and working hard, or we're going to lose a future generation of kids to this epidemic," Arkansas Surgeon General Joe Thompson said.

Arkansas tested 366,801 students out of 472,000 last year. Thompson said absenteeism was the biggest reason why only 77 percent were weighed, though some families formally opted out of the program.

In the previous school year, 20.5 percent of 369,416 tested were overweight, with 17.1 percent considered at risk.

The state began measuring students' body mass indexes annually starting in 2003. The effort was championed by then-Gov. Mike Huckabee, now a Republican presidential candidate who lost more than 100 pounds after being diagnosed with diabetes. Many states have adopted similar programs.

But state legislators this year relaxed the standards. Pupils are now measured in kindergarten and in even-numbered grades, with high school juniors and seniors exempt.

Some lawmakers argued that requiring the BMI screenings could stigmatise youth, particularly teenagers whose eating and exercise habits were unlikely to change. During this year's legislative session, some lawmakers tried first to repeal the required BMI tracking and eventually ended up with a compromise bill that only weakened the law.

"If the children that opt out — or the parents who opt out — are the more overweight children, the data will be skewed," said Jim Raczynski, dean of the University of Arkansas for Medical Sciences' College of Public Health. "It will look like there are fewer overweight children when in fact there aren't."

Raczynski said the reliability of the reports will now depend on the number of students who don't want their BMI tracked.

When Arkansas adopted BMI testing, the state ranked third in the nation in obesity, according to the Centers for Disease Control and Prevention.

Even under recent changes, Thompson said the state will still be able to reach out to children with its BMI reports and through other efforts to cut down on obesity among youth, such as limits on junk food sales at schools.