Lizzie Velasquez weighs just 4 stone but she'll be the first to tell you she's not anorexic. Lizzie, 21, has a rare and undiagnosed syndrome that prevents her from putting on weight, so she remains skinny. Despite the fact she eats high calorie food every 15-20 minutes she remains skinny and the same weight as the average 8-year-old. Doctors are still unsure what condition Lizzie may have that keeps her so thin but they have found two similar cases of women that can't put on weight, one in the UK and one in the US. Despite some medical problems that mean she remains thin Lizzie leads a full and active life. She goes to university in Texas and hopes to become an motivational speaker.