85-120 Maybe Even 140?

Can you help me because my friend get's on buging me to help him but,i need your guys help. My friend is 15 years old and his 5'5 and he weights 85 pounds. He wants to gain weight but his moms says he should fruit,vegetables,chicken,and quit drink soda and other things. I think she's right,but he says she does cook chicken but too much vegetables. He eats pizza,chinses food and A Quater pounder with cheese at Mc.Donalds ,he thinks that will help him gain weight and he has bee trying this since january,could you help me out and he wants to gain aleast 100 pounds before school beging because he's going to high school,you have any answers that that would be good,and me too..i'm 100 i would like to gain 40 pounds, and i'm 15. If i could get 20 pounds more that would be good, like (120)i'll be happy so could you help us. Yeah just 120 POUNDS,IF MORE THAT'S GREAT!