April 16 (Bloomberg) -- Obese teens who undergo stomach surgery to promote weight loss will be the focus of a government- funded study to determine whether the procedure is appropriate.

Doctors at four medical centers will study 200 teens before, during and after the surgery to reduce stomach size, the National Institute of Diabetes and Digestive and Kidney Diseases said in a statement. The study will cost $7.8 million over five years.

About 17 percent of young patients ages six to 19 years old are considered overweight, and as a result they're at increased risk of serious health conditions such as diabetes and heart disease. Doctors want to know whether stomach surgery can help children avoid serious weight-related problems, such as high blood pressure, said Thomas Inge, a surgeon at Cincinnati Children's Hospital Medical Center in Ohio.

``It may be that once you have these problems for decades, they become so severe that not even weight loss surgery can reverse them,'' said Inge, who's leading the study, in a telephone interview.

Surgery is an important option for extremely obese teens, Inge said. Weight control is difficult to achieve with just diet and exercise, and weight loss drugs are approved only for children 16 and older.

Researchers will compare the progress of teens who undergo stomach surgery, also called bariatric surgery, with 200 adults who have had the procedure, Inge said. Researchers from Texas Children's Hospital in Houston, Children's Hospital of Alabama in Birmingham, and the University of Pittsburgh in Pennsylvania will also participate.

The study is called the Teen Longitudinal Assessment of Bariatric Surgery, or Teen-LABS. Teens 14 to 19 years old are eligible to enroll, the statement said.

A government study of stomach surgery in adults that started in 2003 has enrolled more than 4,000 patients and will continue through 2008, researchers said in the statement.

To contact the reporter on this story: John Lauerman in Boston at jlauerman@bloomberg.net.

Last Updated: April 16, 2007 18:00 EDT