Both anorexia and bulimia increase the risk of death. In the developed world binge eating disorder affects about 1.6% of women and 0.8% of men in a given year. Anorexia affects about 0.4% and bulimia affects about 1.3% of young women in a given year.
If you are insisting that on average a page is 500 words or 4,000 words the equivalent of 8 pages. By simple math you saying the average book is 80,000-120,000 words, would mean on average a novel is 160-240 pages. These would be classified as short novels or more so novels for older kids or younger teens.
a young adult book is usually 150-300 pages long. that is the common length. however, books can vary in page length. For example, Harry Potter is around 500-1000 pages long. and Twilight was about 300-500 pages long. so it all depends. as long as the novel you are writing centers around concepts/themes for young adults then it doesn't really matter what the length is. Usually young adult books are 200 or 400 pages.