The woman’s hips bulged in unsightly saddlebags. Then she had liposuction and, presto, those saddlebags disappeared.

Photo after photo on plastic surgery Web sites make liposuction look easy, its results transformative. It has become the most popular plastic surgery, with more than 450,000 operations a year, each costing a few thousand dollars.

But does the fat come back? And if it does, where does it show up?

Until now, no one knew for sure. But a new study, led by Drs. Teri L. Hernandez and Robert H. Eckel of the University of Colorado, has answered those questions. And what he found is not good news.

In the study, the researchers randomly assigned nonobese women to have liposuction on their protuberant thighs and lower abdomen or to refrain from having the procedure, serving as controls. As compensation, the women who were control subjects were told that when the study was over, after they learned the results, they could get liposuction if they still wanted it. For them, the price would also be reduced from the going rate.