I am interested in this also, as i am rather skinny, and no matter what i eat i can NEVER put on weight (this is prior to pilling as well)
What kind of build are you? have you always been kinda skinny, and find it hard to put on weight?
First thing to do, EAT HEALTHY!! If you eat heaps of fat you might put on some fat weight, but hey who wants that?
I have been eating healthy for the past 1 month or so and i feel fantastic, maybe its just a mind thing, but hey ill take whatever i can get to feel good :D
The main secret to putting on weight, is to EAT MORE (shock horror?!) For example instead of 3 large meals a day, spread it out to 5 smallish size meals, your body will then have a constant supply of fuel to grow!
Be careful of doing heaps of cardio stuff, (excessive amounts can hinder muscle development, dont get me wrong though, i still exercise with a weights program on top)
Get into some weights, eat high protien foods. Maybe instead of one of those meals, have a protien shake instead! Ive gained 2 kg in a month or so (which is a real acheivement going from 55kg for the past 2 years).
if your a skinny person like me check this site out:
www.skinnyguy.net (i think its .net it could be .com or some other extension, if that doesnt work google it!)