I was impressed by ANS's answer. Are you a doctor by any chance ANS? Follow his advice it really sounds right on the spot.

I really think that if you eat normal and eat healthy then you have no need to worry about your weight. A visit to a doctor to make sure everything is OK and then stop worrying cause not everyone is the same and being thin might be normal for your body.

But my friend you have an enviable position there. I am sure that many of us would love to trade with you cause I'm 5' 6'' and am 150 lbs. It's not a problem I know but I have a potbelly that I would love to get rid of.

Before you gain weight, everyone wants to be heavier but once you gain weight then you want to go back to being skinny again and that is as everyone knows very very hard. Very easy to gain but not easy to lose :(

Good luck with your weight thing.