Norwood, Massachusetts (CNN) -- One-third of America's youth is now overweight or obese, according to the Centers for Disease Control and Prevention.
In Norwood, Massachusetts, 14-year-old Maria Caprigno no longer wants to be one of those statistics.
Maria has been overweight since she was about 3 years old and as she got older, she just got heavier. She told CNN her eating habits were to blame.
"I'm a junk-food person and because I'm a couch potato I don't like to get off the couch," she said. "It's also kind of just like my genes: Both my parents are heavy and that's just the environment I was raised in."
Maria said people have stared at her all her life because of her weight.
"The first thing that goes through their mind is, 'Why is she so fat?' And, 'Oh my god, she's so fat. Why doesn't she just hop on a treadmill?' And I think people don't really understand that it's not just exercising ... it's extremely hard.
See Maria growing up in pictures
"I get self-conscious," she said. "I don't like to go to crowded places -- like if a mall's crowded, I'll sit in the car."
The CDC says obesity rates for Maria's age group, those 12 to 19 years old, have tripled since 1980. Maria pleaded with her mother to find a doctor who would perform weight-loss surgery on teenagers.
Dr. Evan Nadler, who started a program for adolescent surgery at National Children's Hospital in Washington, said he felt "compelled" to help Maria.
"Her BMI [body mass index], which is a measurement we use to determine how obese someone is, put her in the highest risk category. Not just morbidly obese but two categories higher than that," Nadler said. "So I felt that withholding a known therapy that works based on her age alone was really almost unethical."
Between 2000 and 2003, some 800 teenagers went under the knife to lose weight, Nadler said.
Before she was approved for surgery, Maria had to meet with a nutritionist, a pediatric cardiologist and a psychologist. In the end, Maria was approved for an experimental procedure known as a "gastrectomy," during which about 80 percent of the stomach is removed, including the part of the stomach that controls appetite.
Nadler said the procedure "basically restricts the amount of food that can come into the stomach at any one time and it really makes the patient have a sense of fullness or a lack of hunger."
Maria had the "gastrectomy" last month and already has lost about 45 pounds. Today she weighs 400 pounds and is down to a size 32. Maria said she would like one day to be a size 12 but isn't trying to reach a specific weight.
"It's not about the numbers; I want to be at a healthy size," she said.
"I want to be able to go into a normal store and buy something and be able to wear it. I want to be able to run. I haven't been able to run since I was 5 years old. I want to be able wear a bathing suit without feeling embarrassed.
"I just want to be normal."
But Dr. Edward Livingston, a Texas surgeon who also has helped adolescents lose weight, said surgery for teenagers can be risky. He has turned away most teens sent to him for evaluation, he said, and has operated only on those more than 500 pounds with serious health risks such as blood clots and congestive heart failure.
"Adults are a different matter because they are more emotionally mature," Livingston said. "They know what risks they want to take and they can buy into the procedure. Kids don't really know what they're getting into, so I think you have to be really careful with children before doing these operations on them."
Livingston noted that only a limited number of studies have been done on weight-loss surgery's effects on teenagers later in life.
"We don't really know the full spectrum of positive or negative outcomes for the procedures," he said.
Nadler, who operated on Maria, said he fully agrees that "we need to study this more. But I don't think it's fair to the Marias of the world to keep them from having this procedure based on their age alone."
In his own study, Nadler followed 41 teenagers for two years after weight-loss surgery. He said they lost half their excess body weight and their health had improved.
Maria said she was well aware of the risks of surgery, but after trying about a dozen different diets, she said, surgery was her only option. Now, she said, she is well on her way to becoming a healthy teen and adult. She works out playing the Wii video game and walks every day with her brother after school. She is eating a high-protein diet.
"This surgery is a tool in your tool box to becoming healthy," she said. "It is not the quick fix. You need a lot more. You need to exercise you need to make the right food choices."
In a letter to the insurance company seeking coverage for this procedure, Maria wrote she needed this surgery to make it to her 15th birthday. She said, "Doctors have told me for years that if I keep gaining weight I'm not going to see 18 and that has terrified me. I want to live. I want to do so many things."
