Right firstly BMI = RUBBISH i wouldnt worry because if you think about it, a 20year old male at 6ft 5 and a 60yr old man at 6ft 5 should be the same weight??? rubbish, both of their bodies are different due to age...bmi does not include details that are essential like age lifestyle, ect it GENERALISES everyone like chickens. i wouldnt worry about that! Secondly - i also find it hard to gain weight more so now i have ibs, but i see it as if ur eating and its enough for you to function and ur not loosing alot and look dead your fine. =) ive always been picked on for being slight even when i was a child at school, its just life, some people are fat some people are skinny some are inbetween. im 5ft 3" and weigh nomore than 6stone! worryin will only make ur issue worse mate! Thirdly - have u had a food allergy test?? x