Katie was proud as she placed the plate on the carefully-laid table. She didn't usually cook, but it was good to know all those hours of watching cookery programmes had paid off. Her mother always said she was a quick learner. The cooking had actually turned out to be a pleasure. Katie wondered if she should invite some of her university friends over to show off her new-found skills. Not that she had many friends. In any case, she didn't know yet if this meal was as tasty as it was aesthetic.

Putting off the moment when she would have to sit down and spoil her creation, Katie stood back and admired the sight. The tablecloth was dark burgundy, the single plate a light purple; the dark colours of the tableware contrasted pleasingly with the whiteness of the meal. A glass of white wine completed the picture. Katie felt like taking a photograph. But the hardest was still to come.

You can do it, she told herself firmly. Don't let Her win.

She took a deep breath and sat down at the table, unfolding the napkin with a sharp shake. Katie laid the burgundy cloth on her knee. She could smell the food and it terrified her. Part of her was screaming that she should get up and throw the whole thing in the bin.

"I can do this," she said out loud. Lifting her head, Katie fixed the painting hung on the bedsit wall. "You're not going to win."

The painting was one she had done just after she started her art course at university. It represented a witch with a thin, gaunt face and long coarse hair. The creature's expression was malefic, as if it was hatching some devious plan for its hapless victims. The painting was one of Katie's many attempts to exorcise the demon inside her, to get rid of the invisible disease which made her waste away. The witch was also a caricature of herself, a stick insect of a creature with sunken cheeks and a razor-sharp chin. It was only natural that the disease which had been Katie's closest companion all her life should look like her. The only real difference was in their names. The picture simply bore the deceptively-attractive name of Katie's only friend and long-time enemy. Anorexia Nervosa.

Staring at the picture gave Katie a new resolve. She pulled her chair closer and re-arranged the napkin on her knee. She moved the fork and the knife so that they were perfectly aligned with the plate. Then she picked up the glass of wine and placed it three centimetres above the tip of the knife. The pieces of bacon were scattered unevenly on her side of the plate, so Katie turned the plate around to find bacon with a more symmetrical pattern. When she had done that, she realised that the parsley on the top looked askew. She reached over to pick the sprig up and place it in a different position. In doing so, one of her nails sank into the thick sauce.

Katie withdrew her hand as if the dish was on fire. She stared at the white sauce on her fingertip, her breathing shallow and her heart beating fast. Put it in your mouth, she told herself. That's what a normal person would do. Put their finger in their mouth and taste the delicious sauce. But Katie knew it would take superhuman effort for her to perform this simple task. The distance between her finger and her mouth seemed immense.

She decided that it wasn't proper to lick one's fingers anyway. Pushing her chair away from the table, Katie went back to her cooking area and wiped her finger with a paper towel. There was a small quantity of flour on the worktop, so Katie got a sponge and wiped it down until it was immaculate. For good measure, she also cleaned the cooker.

Katie put the sponge back in its customary spot on the sink and turned to look at the table. There was no smoke rising from the dish anymore. Katie looked at Anorexia's picture on the wall and took a deep breath. She knew that the only person who could ever defeat Anorexia was herself. Doctors, psychiatrists, her parents and friends; dozens of people had tried to help Katie over the years, but no one had ever managed to defuse the autodestruct mechanism inside her.

Intellectually, Katie understood what was happening to her. A doctor had explained it to her once. For some unknown reason, her brain was in a perpetual state of anxiety which made her unable to concentrate on mundane things like eating. Because eating was such an essential part of human existence, the constant social pressure to eat increased Katie's anxiety, effectively placing her in a vicious circle. She couldn't eat because she was stressed, and she was stressed because she couldn't eat.

So much for the theory. But in practice, nothing could break the cycle. Katie had been in and out of clinics. She had spent hours with similarly afflicted waifs, sitting at a table staring at food while a nurse stood over her to make sure she ate. That approach had done nothing to reduce her anxiety. In fact, Katie's last stay in an eating-disorder clinic had ended with her throwing her full plate at one of the nurses, too frustrated with herself and with the system to complete her course of treatment.

Doctors had also tried prescribing pills. These were designed to relax Katie, and they did make it easier for her long-suffering parents to feed her. But they also made her sleepy and unresponsive. Katie had finally decided that she preferred to live a short life as a sentient, starving person rather than a long one as a zombie.

There had been a lot of counselling, too. A psychiatrist tried to uncover any traumatic event which might have made Katie anorexic, but there was nothing out of the ordinary. The triggering event had been simply Katie's family moving from one neighbourhood to another when she was twelve. Someone at the new school had called her "fat arse" once. Katie found it difficult to believe that such anodyne events could have caused such a lifetime of misery. It was easier to believe that she was simply born with a defective brain or something.

Everyone around Katie was trying to help, from her ever-loving parents to the dedicated nurses and doctors who treated her time and again. But Anorexia's hold on Katie was unshakeable. There were good times, when she could eat more than once a week; there had even been times when she put on weight. But there were also bad times, when Anorexia would not let Katie eat so much as a biscuit a day. This was one of the bad times. Katie was twenty-one, an A-grade student with lovely dark hair and big blue eyes. She was young, she was pretty, she was talented, and she weighed four stone.

Still standing in her kitchen area, Katie fixed the picture of Anorexia again. The witch seemed to be mocking her, laughing at her inability to help herself.

"You haven't won yet," said Katie firmly.

She went to sit at the table. This time, she didn't fuss with the napkin or rearrange her cutlery. She purposefully seized the fork, dug it into the pasta and twirled it to pick up a small quantity of tagliatelle and sauce. Katie smiled triumphantly. One mouthful of food and she would win.

The fork was halfway to her mouth when Katie's hand stopped. The food was cold and gave out no smell. The aesthetics of the plate had been spoiled. There was a crease in the table cloth. A small clump of hair from Katie's brush lay near the sofa. She really should hoover the place again. It got so dirty even after a scant twenty-four hours.

Katie reined in her wandering thoughts and turned her attention back to the fork. It was poised between her and the plate, ready to cover the small distance to her mouth. Open mouth. Put fork in mouth. Chew. Swallow. It was so simple, so natural. So hard.

A sob escaped from Katie's lips before she even realised it was coming. She dropped the fork and a hiccup shook her bony frame. She almost imagined she could hear her fleshless bones collide. Anorexia was too strong. It had claimed so many people before her. Karen Carpenter and the child star Lena Zavaroni had been defeated by it. How could Katie think she would fare any better?

Katie raised her eyes to the picture again. The witch was blurred by her tears, but the malevolent smile was unmistakable.

"You can't do it, can you?" Anorexia seemed to say. "You can't leave me. I'm your friend, your long-time companion, the only thing that stands between you and the horrid world you live in. You can't live without me."

"No," sobbed Katie. "It's not true. I can be normal!"

"Normal?" scoffed the figment of her imagination. "How do you know what normal is? You've never been 'normal'. You're mine, Katie, and you always will be. I'll never abandon you. I'm your only true friend. You should know that."

In spite of herself, Katie nodded. There had been times in her life when Anorexia did seem like a friend. It was as if there was a hollow inside Katie which Anorexia seemed to fill. Somehow, the disease had stopped her from growing up; her starved body did not menstruate, and she had always been too focused on food to have boyfriends or socialise with her peers. Katie had only recently found the courage to leave home. Anorexia had built a comforting cocoon around her. The disease had insinuated itself into her life until Katie did indeed find it difficult to imagine life without Anorexia.

But life with Anorexia meant a certain death, and Katie knew she had to fight back. If not for her own miserable sake, at least for that of her parents. They had already suffered so much on her account. It wouldn't be fair to let Anorexia deprive them of the only child they had fought so hard to keep.

"You're not going to win," said Katie firmly. "I'll show you."

She picked up the knife on the table and walked up to the picture. She stabbed the witch right in the face. The canvas ripped with a satisfying tearing noise. "I'll show you," she repeated.

Katie walked back to the table. Without sitting down, she picked up the fork on the floor and plunged it again into the cold, congealed food. Her mouth went dry and she could feel her pulse racing. It would be easier for her to touch a spider than to take a mouthful of food. But this was the only way to beat Anorexia.

She closed her eyes and forced the fork into her mouth. The slimy pasta stuck to Katie's dry lips. She mechanically closed her teeth on the fork to detach the food as she pulled the utensil out again. She fought a surge of nausea as she began to chew. The cold tagliatelle had no taste, and Katie felt as though she was eating dust. She fought the impulse to spit the food out. Instead, she swallowed with one big gulp.

Exhausted and trembling, Katie looked up at the torn picture and smiled. Her war with anorexia wasn't over, but the one mouthful was a battle won. "Goodbye, my friend," she whispered. "I won't be needing you anymore."