How do I gain weight? (Repost)?

I'm extremely skinny for my height and age and I know it's because of my fast metabolism. My doctor told me to start working out if I wanted to gain weight, so I did and have been for about 3 months now, problem is I only gained 6 pounds! I'm 5'9 and I only weigh 102 pounds, yes, you read right. I'm starting to get scared because I turn 17 in 2 weeks and I still don't weigh even 125 which is what most GIRLS my age weigh! I'm a guy so this is obviously a bad thing when I'm skinnier than the girls around me. Yes I do eat, infact most of the time I eat the same as the adults around me that weigh 100lbs more than I do, so why is it so hard to gain weight? Any advice/tips would be greatly appreciated, thanks.

How to Lose Weight Without Relying on Exercise

Recommended Answer:

So 1 week. Your parents are gone away, and your home alone, this will only work if you have money and a car to drive. Drive to a bulk barn (i dont know if the USA has them) or a candy shop. Buy a weeks worth of candy, and eat nothing but candy all week long. And put a friend in there he will help you eat all that junk food.