The last five pounds. The vanity  pounds. The dream weight. The fantasy weight. The high school weight. Yes, many names are given to the weight - the five pounds - that seems just out of reach no matter how much we exercise and improve our eating habits. But why is it out of reach? Is it all in our heads? Or is it because the body has a set-point or ideal weight - a weight to which it doesn't want to give in? "There is no such thing as ideal body weight," says James, author of "Weight Loss That Lasts." "But your body does resist you when you are trying to lose weight. It gets used to a certain weight over a long period of time and then will defend that weight." In other words, the body's "set point" can be lowered - or raised, he says, but it takes time to reset that new weight. That period of time is at least six months. "I often ask patients, 'What is the lowest stable weight of your adult life?' to get an idea of what is realistic" in terms of weight loss and maintenance , James says. He refers to the body's refusal to change, weight-wise, as an "biological control system that prevents us from going hungry and dying - part of our primitive  biology." Some people might get down to their dream weight for a short period but then can't keep it long because the calorie limits are too strict once the body starts defending itself against weight loss. "That's why it's important to set realistic goals," he says. "The idea of the 'ideal weight' or 'dream weight' is really just a useless exercise." But let's say your goal is realistic and has been set by a nutritionist  or other weight-loss professionals and _ . What could be going on? The reason is that you need fewer calories the less you weigh. So if you want to continue to drop weight, you have to drop calories and increase calorie-burn. James encourages people to tell the difference between weight loss goals for health reasons and those to do with vanity. "They are different issues," James says. "One is where important health benefits are seen and the other is about vanity - wanting to look good in a bathing suit." People can't keep their dream weight for a long time because  _  .
the body system stops us from hunger the calorie limits are extremely strict we haven't turned to nutritionists for advice we can't keep the habits of dieting for six months