Mainers who suffer from morbid obesity are increasingly turning to a surgical operation called gastric bypass. They learn about it from their physicians, by word of mouth, and through national publicity including the story of Carney Wilson, the popular singing star, who says it slimmed her down and changed her life. In Maine, there were 250 such operations in 2000, and the number is rising. Dr. Donald M. Clough, in Bangor, says gastric bypass now amounts to 80 percent of his practice. He often does two a day, but he and others warn it’s not for everyone.

The operation consists of reducing the size of the stomach by surgical means such as stapling or banding the stomach. It can be performed either through an abdominal incision of six inches or so or by laparoscopy, using camera and instruments through much smaller incisions. After three or four days in the hospital, the patient gradually recovers, must adopt a special diet, satisfyingly eats less and greatly reduces weight.

An Internet video about “Edna,” who underwent the operation last year in Mississippi, shows successive pictures as she went from 318 pounds on July 4, 2000, down to 150 pounds on Aug. 25, 2001. Other patients compare notes in a Yahoo! chat room.

Maine’s director of public health, Dr. Dora Anne Mills, reflects the advice that the surgeons invariably give: Gastric bypass is not for everybody who is overweight. It is right only in cases of “morbid,” or life-threatening, obesity, when other methods such as nutrition counseling have failed.

The operation was developed by an Iowa surgeon, Dr. Edward E. Mason, starting 30 years ago. Dr. Richard Hornberger, who practiced in Bremen, Maine (and wrote a book that led to the 1970 movie “M*A*S*H” and a television series), did the operation. He came to Bangor in 1979 and taught Dr. Clough and Dr. Dan Maunz how to do it.

Dr. Clough describes the typical gastric bypass patient as a woman so heavy that she suffers discrimination socially and on the job, can’t ride in an ordinary plane seat, has to walk down stairs backward because she can’t see the steps, and can’t do anything about overeating. Such people face an eight-fold increase in the chance of sudden death at an early age. He accepts applicants for the surgery only after counseling and screening. He insists on at least 100 pounds overweight and won’t take those who abuse drugs or alcohol or smoke cigarettes.

Gastric bypass is major surgery and carries the usual risks. It can cost from $15,000 to $45,000 or $50,000. Health insurers generally pay much of the fee, while insisting that a patient meet strict criteria.

As Dr. Mills, Dr. Cough and the American Society for Bariatric Surgery keep warning, the operation carries risks that must be considered against the potential benefits. But for those who meet the criteria, the operation provides one more option for a healthier life.