My secret to gaining weight (I get yelled at for not gaining weight.......) is to eat HEAPS. Like I eat 5-7 times a day and during the weekends and holidays I eat constantly.......well normally. Eating alot of high fat, cream and lots of other foods like that. Just eat lots and lots and lots of them. But don't take my word, ask a CF dietican, they are really helpful. Cos I was always tired during swimming and they helped me to find some high energy foods and so now I can swim the 4km and not be that tired.....tis excellent.