By Cynthia Sass, M.P.H., R.D. for Shape.com
Losing weight is one thing, but keeping it off is the true challenge. That's why researchers from Brown Medical School and the University of Colorado started a database called the National Weight Control Registry, which tracks more than 5,000 people who have lost an average of 66 pounds and kept it off for more than five years -- without gastric bypass surgery. Through communicating with this group of successful weight-loss losers, they've identified four things people who keep the weight off have in common.