I am 21. I am 5'7" and weigh about 145. I haven't ever really had too much trouble keeping weight on, although they had me on enzymes when I was younger. I, personally think that I was just naturally a skinny kid, and always had pancreatic function. When I was in high school, I gained about 20 pounds and grew about a foot in a year. Needless to say, I stopped taking the enzymes after that. lol.
Marisa,RN, 21 with CF