The study in the journal Pediatrics looked at weight loss surgeries done in California between 2005 and 2007.
It found 590 teenagers ages 13 to 20 had either gastric bypass or the lap band procedure.
With that procedure surgeons laparoscopically tie a band around the stomach so people feel more full. It is not FDA-approved for teenagers under 18 years-old.
Kayla Maryles had the procedure done when all else failed.
She believes approval should be based on health risks, not age.
"I've lost 80 pounds. My life changed in many ways, most of all my eating habits and the food that I eat," Kayla said.
Many experts say the benefits of surgery, helping overweight teens lose weight and prevent problems such as diabetes and high blood pressure, outweigh the risks.
Other experts argue we still do not know the long-term effects.
