Gastric bypass procedures have worked far better than anyone expected. Not only does it help obese patients lose weight, resulting in longer (and improved) lives, it has changed the way we think about obesity. The unprecedented success of these procedures has spawned whole new areas of research, including drugs that kill appetite signals and surgical procedures for helping normal-weight diabetics. How did this once rare and "last-ditch" procedure become one of the most effective treatments for the growing obesity epidemic? Claire Ainsworth explores the history and future of treatments in NewScientist.