Frequently, people who diet to lose weight become trapped in a vicious cycle. When those people diet, they not only lose weight, but their bodies become used to fewer calories and become accustomed to functioning at that lower rate of caloric intake. As a result, when they stop dieting and go back to eating amounts of food that would have just maintained their weight in the days before the diet, they take in far more calories than they need. Those excess calories produce excess weight. The passage above best supports which one of the following conclusions about people who diet to lose weight? ['They are bound to end up weighing more than when they started dieting.', 'They must not go back to eating pre-diet amounts of food if they are to maintain their weight at the reduced level resulting from dieting.', 'They never can go back to their pre-diet caloric intake without regaining all of the weight lost by dieting.', 'They should not diet if they desire to maintain their reduced weight.']