Governor Christie secretly underwent weight-loss surgery in February, just days after joking about his weight with David Letterman. John Meilahn of Temple University Hospital, a surgeon who was not involved in the governor's care, says a silicone band is placed around the stomach and tightened every four to six weeks. How much weight someone loses can vary. "Typically, we will see 30-50% excess body weight. That means if you are 100 pounds overweight, you might lose 30-50 pounds of that weight," says Meilahn.