KANSAS CITY, Mo. (AP) — Sixteen-year-old Jason Alexander weighed 326 pounds four months ago when he and 13 classmates boarded a plane for a weight-loss boarding school in South Carolina.

When he stepped off a flight home Friday, he was down to 233 pounds, making him the biggest loser in his Missouri school district's unusually aggressive effort to battle childhood obesity.

While individual families have long enrolled children in weight-loss programs, the Independence school district is believed to be the first to send students as a group to a program like the one in South Carolina. The 12 students who completed the program lost a combined 756 pounds, and relatives and friends who greeted them at the airport could scarcely believe the change.

Jason's mother, Debbie Alexander, said it wasn't just the weight loss. Her son who had battled a speech impediment and been slow to smile was now grinning broadly.

"It's crazy," Alexander said. "Kids have always given him grief."

The school district, its foundation and the students' families worked together to pay about half of the usual $28,500-per-semester tuition at MindStream Academy in Bluffton, S.C. The rest of the tuition was paid by a foundation associated with the academy and other donors.

Jason and the other students — the youngest was 11 — spent the semester exercising, studying, working with counselors and learning to eat healthier. Their parents, meanwhile, met monthly with MindStream's clinical director in Independence to learn how to help their children upon their return. Experts say it's hard for anyone to maintain weight-loss if their families don't also develop good eating and exercise habits.

Several Independence parents said the program also helped them lose weight, from 5 to 80 pounds. The brother of a teen who went to South Carolina lost 36 pounds at home.

Neither the district nor the boarding school knew of any other public schools that had made such an effort. But Sarah Stone, the director of programming at MindStream, said it hopes to engage other districts in similar partnerships in the future.

"It is to all of our best interest for these kids to be able to realize their best potential," Stone said.

Each student had a story of how the pounds added up. Jason's weight shot up after his father's death 6 1/2 years earlier, jeopardizing his dream of joining the military. Like many who are overweight, he became easily winded and his knees hurt.

He said he's now 40 to 50 pounds from being able to qualify military service and plans to join a training group to help him shed the rest of the weight. His family has cleansed the kitchen of junk food, made space for a treadmill and stocked up on healthy items like ground turkey. The district envisions Jason and the other participants becoming health ambassadors in their schools, perhaps speaking to groups or working one-on-one with classmates who are struggling with their weight.

"I feel amazing," said Jason, who shed weight so quickly that he struggled to find clothes. His jeans, which he bought from another classmate, hung loose around him, cinched with a belt to keep them from falling off. "I can't believe I got to that point. I can't believe I got that big."