It's Eating Disorder Week and Newsround's looking at how the pressure to look a certain way can drive some young people to take extreme measures.
Many are teenagers but some are as young as eight years-old. Hayley met Moreven, who wanted to tell her story.
The charity Beat says more than one and a half million people in the UK are affected by eating disorders like anorexia or bulimia.
They say that around 60% of people affected didn't tell anyone about their eating disorder because they didn't know how to talk about it.
Do you worry about the way you look? Do you ever worry about being too thin or too fat? You told us what you think.
"I feel really sorry for people with anorexia, it's a horrible thing to have and people shouldn't be so conscious of what other people think of them. I occasionally worry about my weight but then I think, well, I eat a healthy amount of food and proper healthy meals, I do lots of exercise.... Just be yourself!"
Hannah, 13, Dundee, Scotland
"I feel sorry for people with anorexia, it's unfair that they are bullied for being different. We're all humans!"
Lucas, 12, Wales
'''You are beautiful no matter what they say, words can't bring you down' - Christina Aguilera."
Jade, 12, Essex, England
"I hate magazines because they put pressure on people to lose weight. I also hate bullies who destroy people's self esteem and make them feel like they should look a different way or lose weight."
"My family are all naturally slim and I'm the same. People are always asking questions because they think I am anorexic - I am not. I feel sorry for people with anorexia."
Kristyna, 11, England
"I am relatively slim and I have been called anorexic when I am not. I think that the reason teen girls can get eating disorders is because of comments that are made by people who are not thinking about how the comment may affect the person."
Imaan, 11, London, England
"I worry about my weight. I didn't eat for a couple of months but I'm back on track with 3 meals a day. Anorexia is horrible but luckily i had great friends to help me through it."
Robyn, 14, London, England
"One of my friends from youth group has anorexia. Some of my friends and me raise money for BEAT. Sometimes I worry about the way I look. Sometimes I think I'm fat and other times I'll think I'm healthy."
Helen, 12, Hampshire, England
"I feel upset that people have eating disorders because it can totally change who you are."
Rose, 11, England
"One of my friends actually cares more about her weight and body than her GCSE's. She's ruining all her school work and course work, just because our society and the media make her feel bad about herself. She is slowly developing anorexia and often skips meals and when she does treat herself to something nice to eat she feels bad after. It's awful."
Maddie, 14, England
"At school people constantly say I'm skinny and I try so hard to eat more but never notice a difference? I think people need to just get a life and not try to ruin others."
Callum, 12, London, England
"Many children are worried about the way they look because of peer pressure. People are bullied for being thin or fat. My most frequent question asked at school is 'do you ever eat?' Of course I eat, or else I wouldn't be able to run cross country or swim. You shouldn't worry about how you look, just be yourself and be happy with it, that's all that matters."
Anon, 13, England
"I think anorexia is horrible and I feel so sorry for anyone who has it. I like the way I look and I hope other people do too. My advice to help you feel good about yourself is just to keep smiling through thick and thin! Then you will always show your better side to anyone who may be watching you!"
Hannah, 12, Scotland
"Everyone feels upset or uncomfortable with the way they look at some point or another... it's life. People with things such as anorexia shouldn't have to put up with people calling them names and insulting them because of the way they are. It's not their fault."
Ellie, 14, Surrey, England
"I feel very sorry for people with anorexia because it can quite easily become life-threatening without any medical help. It can be really serious and it can make the sufferer feel like a different person."
Ruby, 12, Lincoln, England
"I feel sorry for people with anorexia. People should be strong and not care about what other people think. People who tease people for being anorexic are bullies."
Eleanor, 9, Gloucestershire, England
"Sometimes I worry what some people think of me. I'm not anorexic myself, although I'd advise people to eat well and NEVER skip meals."
Erin, 11, Belfast, Northern Ireland
"I always worry about my weight. I skip breakfast and lunch, but not intentionally. I just don't find time and I get moaned at by my mum constantly."
Sarah, 12, Bolton, England
"When I had problems in the past, I never knew how to show they existed. I don't eat much anyway but I knew anorexia would just ruin my life. Needless to say, I still worry about my spots, my hair... but it's what's underneath your skin that really matters."
Katy, 13, Lincoln, England
"I feel sorry for people who have anorexia. They always get bullied at school. Nobody is perfect and everyone is beautiful in their own way!"
Jordan, 13, Birmingham, England
"I am constantly worrying about how I look and what people think of me. A lot of other kids from school have called me fat and made me feel like a waste of space. I keep trying to think positively but they always put me down."
Jessie, 13, England
"I always worry about the way I look and what people think about me but I've realised that I should put myself first and not care about what others think."
Laila, 12, Birmingham, England
"I'm anorexic and loads of people call me names, I try to change but I just can't help the way I eat."
Rose, 14, Midlands, England
"I feel very sorry for people who have anorexia, it can make them act like a completely different person."
Sameena, 13, England