If you've dieted more than once in your lifetime, you know that dieting is not often the hard part - keeping the weight off for good, is. Dr. Proietto, a physician at the University of Melbourne, decided to investigate why seemingly motivated people who can lose weight, can't keep it off. He decided that maybe the problem had something to do with the body's "biological state."  He and his team recruited 50 obese men and women in 2009. Men weighed, on average 233 and the women weighed around...