Diane Nellis was worried about the health of her teenage son who weighed 240 pounds. But she didn't put him on a diet. Or send him to a fat camp.

She took him to a hospital.

There, Trevor Nellis, 17, learned to limit portions to the size of his fist, cut out fast food and soda, and eat more fruits and vegetables. Six months later, he has lost nearly 40 pounds and runs three miles a day.

As the waistlines of America's young keep expanding, more hospitals are establishing weight management centers for kids. The programs offer a variety of resources, from nutritional counseling to bariatric surgery for the most extreme cases.

"We try to promote healthy behavior for a lifetime," said Dr. Goutham Rao, clinical director of the Weight Management and Wellness Center at Children's Hospital of Pittsburgh where Trevor got help.

Rao said that when the hospital began planning for the clinic about three years ago, there were about half a dozen similar programs across the country. Now, there are around 50 and more on the way, he said.

The clinics are opening at a time of skyrocketing obesity rates among U.S. children. Nearly 1 out of 5 is obese, according to government figures, putting them at a greater risk for diabetes, heart disease and a host of other problems.

Dr. Sandra Hassink, director of the weight management program at the Alfred I. duPont Hospital for Children in Wilmington, Del., said she's seen patients getting younger and heavier since she helped start the program 18 years ago. Her youngest patient was 5 months old.

"It's scary and we're going own. It was the 12-year-old's first visit and she was waiting to get into the BodPod, an oval, space-age looking contraption that checks kids' body-mass index.

Abigail was referred to the hospital by her pediatrician, who noticed she had been steadily gaining weight.

"It embarrasses me," the girl said.

Her mom, Jamie Auria, who is a diabetic, hopes the center will help her daughter change her lifestyle and avoid getting diabetes herself.

"We don't want to add any risk to what she already has to deal with," Auria said. "But knowing and understanding and actually doing are two different things."

Down the hall, Trevor and his mom proudly talk about all he's accomplished with the center's help. Trevor said talking with doctors about weight loss was different from discussing it with his parents.

"I heard it all the time," Trevor said, "but something like this really motivates you to do it."