Hi, I am a male 23 and 5" 10 taller, and the recent weight I measured was 54 Kg. So, the problem with me is that I am too skinny and according to my height I am too underweight at least it should be 63-65 KG something. I don't think the problem could be with my nutrition. Since, I eat a lot, of healthy food. My day starts with regular pushups, sqats, and ab crunches at home. After this work-out I consume a two full glass of banana shake a day. After that breakfast with at least two sandwiches or a bowl full of cornflakes. Twice daily meal and yes some season fruits, too. I didn't prefer oily and fast-foods. That's a basic idea of what do I eat. I need to know what could be the problem? is there any malfunction in my body that stops me in gaining weight? should I visit any doctor? for what kind of checkup if you would suggest any?