, one teenager describes the emotional reassurance she derives from vomiting up her dinner, as well as the practicalities of how to purge in private and avoid vomiting on your shoes.
"I hear it so often: `I could never be bulimic. I hate throwing up'," she says. "Yeah? Me, too. I laugh every time, because it implies I must have started purging because I have some weird fondness for throwing up."
Like anorexics, most bulimics are female and usually middle class and academically overachieving. But the need to binge, followed by an equally strong need to throw up, can be all-powerful, to the point where it takes precedence over all else, including academic success.
In fact, deteriorating schoolwork is often a sign of the disorder.
Many bulimics arrange their lives around their obsession. They play truant to fit in binge-and-vomit sessions. When they are not eating, they are planning their next binge, which distracts them from lessons.
"Classes were no longer a priority," one girl writes. "Homework and papers were something I did while waiting for food to cook, and between binge- and-purge sessions."
Another bulimic writes: "School, friends and anything that once meant something to me were now secondary . Life now revolved around food: reading about it, looking at it, finding it, buying it and binging and purging."
Another contributor writes how she became too weak to walk to school during the last term of her GCSEs. Despite this, she managed to achieve A* grades in English and English literature, but Cs in history and art, and D in science.
She lasted only two weeks at sixth form college.
Susan Ringwood, chief executive of the eating-disorder charity Beat, says academic decline can be one of the obvious indicators of bulimia.
"You're trying to control emotions through food," she said. "When that control breaks down, it often affects other parts of your life.
"It's just a general lack of discipline. So you often have someone who always performed very well, until chaos breaks out."
Most of the girls and women writing in the book are recovering bulimics. They all worry about slipping back into old patterns.
"I'm not nearly as healthy with food as I sometimes suggest," one contributor writes. "It's a struggle. It's a daily, hourly, minute-by- minute struggle . It's exhausting living in my head."
- Bulimics on Bulimia, edited by Maria Stavrou, is published by Jessica Kingsley on October 2
TEACHERS' ALARM BELLS
It can be difficult to spot the physical signs of bulimia, as bulimics' weight often remains within a normal range. Calluses on hands from trying to cause vomiting are not a sure sign: many bulimics use other methods.
When someone vomits a lot, the glands in their neck swell. This is often referred to as "hamster face".
Bulimics often eat normally at school, then binge in secret. But teachers can look for someone who goes to the toilet straight after a meal, or spends a long time there.
When pupils are vomiting or using laxatives in school, this usually becomes obvious from the state of the toilets.
Bulimics regularly become disorganised, handing in incomplete or late homework.
Schoolwork can become messy and riddled with errors that would previously have been corrected.
Academic achievement often declines.
IN THEIR OWN WORDS .
"As a teenager, I would hide containers of vomit in various places in my room, under the bed, in the wardrobe and locked in my desk. My sloppy laziness and grubbiness, before I discovered the ease of disposing waste in the toilet, would mean the containers were left in my room for days and even weeks. I would go on a gruesome cleaning spree and find up to several inches of mould growing."
"I have missed so much. The things a typical teenager took for granted were impossible for me. Socialising and having fun can be so difficult when you feel dead inside. People can see through the facade and know you are breaking, even if all you want to do is hide it, cover the scars and halt the tears.
"My last year of school was patchy. I was absent more than present, and in the end scrapped the last term, as I could not summon the strength to even walk there in the mornings."
"I was at sixth form college, 18 and living at home . I felt like I needed to eat and eat and eat . All the money I'd saved dwindled away as I developed a chocolate habit. I managed to block the kitchen sink with solidified fat."