Can i know how to gain weight?

Wow, I wish I had that problem. If your eating and still not gaining weight, my suggestion would be to talk to your doctor, just to rule out thyroid or any other condition that could be causing this. It might just be that you have a very high metabolism or it's in your genes to be tiny. Even if this is the case, your doctor should be able to recommend something to help you. Have you tried protien shakes?

If you try to eat a lot and you can't put on a few pounds, then you are thin genetically. DOn't worry, this is completely normal. Although talk to your doctor, there is a very low chance that he will give your pills.

Some people just can't gain weight. Have you seen a doctor?