Lizzie Velasquez She eats every 15 minutes to stay alive weighs just four stone and has almost zero per cent body fat but she'll be the first to tell you she's not anorexic.
University student, 21, eats every 15mins but weighs the same as an eight-year-old from Austin, Texas, actually eats every 15 minutes just to stay healthy.
The Texas State University student has a condition that is so rare, there are only three known cases in the world. It prevents her from gaining weight even though she eats up to 60 small meals a day.
She consumes between 5,000 and 8,000 calories a day but her weight has never tipped over 4.3 stone.
'I weigh myself regularly and if I gain even one pound I get really excited,' 5ft 2ins Lizzie said.
'I eat small portions of crisps, sweets, chocolate, pizza, chicken, cake, doughnuts, ice cream, noodles and pop tarts all day long, so I get pretty upset when people accuse me of being anorexic.'
Lizzie was born four weeks prematurely weighing just 2lb 10oz. Doctors found there was minimal amniotic fluid protecting her in the womb.
'They told us they had no idea how she could have survived,' said Lizzie's mother Rita, 45, a church secretary.
'We had to buy dolls' clothes from the toy store because baby clothes were too big.'
Doctors could not make a diagnosis so they prepared Lizzie's parents for the worst.
'They told us she would never be able to walk, talk or have a normal life,' said Rita who has two other children with Lizzie's father Lupe, 44. Lizzie's siblings Chris, 12, and Marina, 15, are both of average height and weight.
Despite the grim prognosis Lizzie's brain, bones and internal organs developed normally but she was always very small.
At the age of two she was still only 15lbs - the same as the average five-month-old baby.
'I was normal but really, really tiny,' said Lizzie, who underwent numerous tests at the St David's Medical Centre in Austin with inconclusive results.
Doctors speculated Lizzie might have the genetic disorder De Barsy syndrome but soon ruled it out as it became clear she did not have learning difficulties.
'They kept on trying to figure out what was wrong with her but we treated her like any other child,' said Rita.
Born with two brown eyes, when Lizzie was four the right began to cloud and change hue. Doctors then discovered she had gone blind in that eye.
'They still don't know why it happened but now I have one blue and one brown eye.'
Lizzie was taken to see genetic experts but they still could not diagnose her.
At the age of six, Lizzie's doctors began encouraging her to eat plenty of fat, carbohydrates and sugar.
'They told me to 'just go for it' with anything I wanted at any time,' said Lizzie, who carries food in her handbag and keeps a big stash under her bed in her flat.
In high school Lizzie made friends and gradually came to accept her appearance.
'I started to think: 'Well this is me, like it or lump it,'' said Lizzie.
'I was always the one at the top of the pyramid during cheerleading,' she added.
Lizzie has a weak immune system and has been in hospital many times after catching numerous illnesses.
At 16 Lizzie almost died when her appendix ruptured and at 19 she had a massive blood transfusion because her blood cells were not multiplying properly and she was critically anaemic.
'I was so weak I couldn't get out of bed,' she said.
'My doctors had no idea how I was still alive. I only had half the normal amount of blood in my body but after my transfusion I felt like a new person, it was great.'
Lizzie's case has fascinated doctors all over the world and she is part of a genetic study run by Professor Abhimanyu Garg, M.D. at the University of Texas Southwestern Medical Center in Dallas.
Professor Garg and his team now believe Lizzie may have a form of Neonatal Progeroid Syndrome (NPS) which causes accelerated ageing, fat loss from the face and body, and tissue degeneration. People with PRS often have triangular and prematurely aged faces with a pointy nose.
He said: 'I am aware of a small number of people that have similar conditions to Lizzie but each case is slightly different.
'We cannot predict what will happen to Lizzie in the future as the medical community are yet to document older people with NPS.
'However Lizzie is lucky to have healthy teeth, organs and bones so the outlook is good. We will continue to study her case and learn from her.'
Lizzie doesn't take medication but she relies on vitamin supplements and iron to stay healthy. It is thought she should be able to conceive naturally without passing the condition to her children.
She added: 'I do all the things my friends do, shopping, movies and parties.
'But I hate it when people stare, or make comments. When I meet new people I have to say: "Hi, I'm Lizzie and I have this rare syndrome, I am NOT anorexic."'
Currently there is no cure but her doctors predict if Lizzie keeps eating she has a bright future ahead of her.
She insisted: 'I'm happy the way I am and this syndrome has made me the person I am'
Lizzie hopes to become a motivational speaker when she graduates.
'I want to make a positive difference in people's lives and show them that you can get through most hardships if you are strong, positive and have a sense of humour,' she said.
Lizzie has also co-authored a book about her incredible experiences. It is due to be released in late September and will be available on Amazon.Watch Pictures Small Video documentary movies in youtube
