i need to ask a question about my size, weight and frame I am a 19 year old guy, and today I went to my doctor and was told I am very thin, I have always known this and I hate it,, I want to be bigger and stronger but I dont know what I should do. I havent grown very much since I was 14 years old. Im the same height and weight. I am wondering what is wrong with me, My doc thinks I have some form of allergy to something which is ruining my metabolism , like wheat ?? and that food isnt burning properly, I dont know if this is true. I am going to the hospital to get it checked, but I want an opinion from another doctor and to see what is possibly wrong?? Im 5ft 7, ( 1 meter 70), and I weigh 52.5 Kilos. My bmi is 18, and I am underweight . I dont drink nor smoke . I eat healthy food, with 3 meals a day, I eat mor ethen 5 portions of fruit a day. I probably dont have an extremly healthy lifestyle, I do a lot of work for my university, but I try to cycle(30 mins to an hour) and everyday I do exercises like pushups, pullups and some back exercises. In the past I have only an allergy to nuts , and I have had problems when I was younger with an Hiatus hernia and reflux which is fine now. People have always seen me as small and underweight, which I hate a lot, Everyone seems just a lot more built and taller then me, I know I probably cant help my height, but I probably can help my structure. What could be the problem, why am I so thin and small and should I do anything, I wish I was bigger.