“It's not your illness; why is it such a big deal?”

But it is. It became my illness. True, I didn't starve myself, but after a while, anorexia claimed us all until my whole family was ruled by it and it seemed to be all we were made up of. We weren't people; we were slaves in anorexia's kingdom. Anorexia is good at stealing and kidnapping and controlling. It especially likes to slip inside your body and hold you hostage while it pulls the strings to make you dance.

When my brother was sixteen, he would always finish the leftovers and copious amounts of pizza. I was the vegetarian who was picky and gave him leftovers to finish. I think he loved food – once.

In hindsight, I don't think it began with the bike rides; it had been gradually snowballing for a year. But that's when I began to notice. He would take his bike out for 80-mile rides with only an apple for fuel. When he wore shorts and a T-shirt I noticed that the veins protruded from his arms and legs like contours on a map. He had crested knees that peaked in blocky triangles when he bent them, and his elbows seemed to be sharpened. He had routines: he couldn't eat until he'd worked out. He wouldn't go out until he'd finished. Food was a reward; it could only be consumed once paid for in sweat and road miles. I didn't understand why.

I didn't understand because I only knew about anorexia in the way that most people do: as this vague thing that happens to teenage girls and had to do with feeling fat. I guess I thought that boys were immune. I simply saw my brother's behavior as a feature of his genius rather than an illness that could claim his life.

I don't remember when he was diagnosed or how I found out or whether it even hurt me. I think I probably said “Oh” in an empty sort of way and went upstairs because it was impossible to accept. I guess I thought that the thing's being labeled wasn't any worse than the thing itself.

My summer was spent listening to my parents trying to persuade him to eat and losing every time. It became a war against my brother, even though it wasn't him we were fighting. I probably did normal summer things that year. I know I went swimming and pretended to have fun. I also know that I did a lot of dance. But it is the anorexia parts that I remember most. When I was at my grandparents' house I saw a family photo from the previous year, and that was when I realized just how skinny he'd become. Obviously, I'd noticed him shrinking, but it wasn't until I had the comparison with the happy, healthy brother that I realized he'd become a skeleton. He only looked at the floor, never at me, and he talked in mumbles that I couldn't hear. We had stopped having conversations.

I have this vivid memory of the night before he was admitted to the hospital. My mum was standing there in the sunset light, crying until her mouth was a drawn black hole, and my dad was holding my brother up in the doorway trying to get him to look at her. I was caught in the middle, and my dad was yelling because my brother hadn't eaten anything, and my brother was screaming and trying to collapse on the floor. It was like watching him become a toddler. My mum said, “I'm not good enough at being a mum – I can't keep him alive.” Then I saw him being packed into an ambulance with a heart rate of 27 beats per minute, and I felt both sick and really inappropriately hungry.

He came home a few weeks later, on a meal plan, and put on some weight. Great. But it wasn't. Putting on weight scared him, and from then on he refused to eat, because gaining weight meant he had failed the demands that anorexia were making on him.

I learned to shovel down meals so I could be excused from the table and not have to watch him. He would dig holes in his skin with his fingernails when my parents tried to make him eat. He would clench his hands around his neck like he wanted to break it. Sometimes I went upstairs and stuck my face in my beanbag and wondered if my eyes should be leaking.

To avoid being around him when he ate, I would have friends invite me over. I sometimes got left there overnight because there just wasn't time for me at home. It wasn't that my parents didn't want me at home; I just wasn't a priority. I wasn't the one whose life needed saving. I just had to carry on living it.

He disappeared for several months into an adolescent mental health unit. I did still see him on weekends. We would play Taylor Swift in the car as we drove over, and I can no longer listen to that album without thinking of that time. But I didn't really see him. I saw anorexia; there didn't seem to be any of him left.

I sent him stupid and pretentious e-mails that I doubt he read. I even hated myself as I wrote them. I tried to be funny but just sounded hollow.

I watched “Mean Girls” at a friend's party, and when one of my friends who knew about my brother was explaining the show to me, she said: “And then the anorexic girl gets really fat ….” She broke off, covered her mouth as if she'd sworn in church, and spent a half hour apologizing. I think I'd stopped being a person to them and had become a porcelain doll or a sympathy case.

People at school would complain that their hair was annoying or that they had a Spanish test, and I would be sitting there thinking, My brother is killing himself. Someone told me that I was having a really lucky year because I was cast in two main roles in dance shows, completely forgetting that that year was the most horrific of my life.

When he came out of the hospital with a nasogastric feeding tube still in, everyone told me they thought he'd moved schools. It must have been terrible for him to suddenly have everyone staring at him and being patronizingly sympathetic. In the hospital, everyone had been like him, and now he was plunged back into regular teenage life. He was suddenly painfully different.

He gradually got better, after anorexia had swallowed up over a year of our lives, but I don't think I will ever be the same. He eats now. I don't know if he likes food, but he eats, and we're trying to move on and not slip backwards. Anorexia is a voice in his head, but it is a voice in a box and the box has a lid on it.

I think the hardest thing about anorexia is other people's ignorance. When I told a friend that my brother was anorexic, she replied, “Oh well, at least he'll get nice and skinny.” This girl still complains to me that her legs are “obese” and that she needs to go on a meat-free diet, completely unaware of how much those words frighten me.

I am still terrified of anorexia and of my brother relapsing. He's gone back to biking, and he did 100 miles two days running, which makes me paranoid that he is going to be reclaimed. I'm terrified of girls who have stick figures, who go on diets and don't eat sandwiches at lunch. The sight of their collarbones scares me, and I can't really relax until I know that they eat normally. I know it's stupid, because I'm skinny too and I eat healthily, but it's just another one of anorexia's scars.

I don't know if you ever get over anorexia. It's a tornado. Even once it's over, it takes years and years to rebuild what it destroyed, and even longer to “get over it.” Right now we're all still trapped in the rubble.

I hate myself because he must hate me for not trusting him and for being so paranoid about his health. I hate Weight Watcher ads because I hate the memories of weighing out fractional calories. I hate the way that the world is desperate for perfection.

Sometimes I even think I hate my brother; if it wasn't for him, I wouldn't have lived through this sort of hell. But I love him. Maybe that's why I'm angry – I care so much. But I need to get beyond it, because with hate we only break things, and my family needs rebuilding.