No matter what she did, Cindy Smith just couldn't shed the 60 lbs. she'd gained during her pregnancy nine years ago. She went through over-the-counter weight-loss pills, liquid diets, starvation diets--always with the same result. "I would try it for about a week," says Smith, 38, a customer-service manager at a Houston bank. "I'd lose maybe 5 to 10 lbs., then get discouraged and end up dropping it."
A friend told her about an experimental diet drug being tested at nearby Baylor University, and Smith signed up. For two years, she and thousands of other overweight patients maintained a low-fat diet,...