<p>When Nancy Tucker was eight years old, her class had to write about what they wanted in life. She thought, and thought, and then, though she didn't know why, she wrote: 'I want to be thin.'<br><br>Over the next twelve years, she developed anorexia nervosa, was hospitalised, and finally swung the other way towards bulimia nervosa. She left school, rejoined school; went in and out of therapy; ebbed in and out of life. From the bleak reality of a...