Okay well im a teen and i have a sister who is 17 who, like me, has CF. We are both pancreatic insufficient yet she has neever had a problem gaining weight unlike me. She is 5ft 8 and used to weigh 158.4. She started not really following the typical CF diet, and restricting what she eats. She now weighs 149.6, and while its not a huge loss its on purpose and she's striving to be 143. Is it just me or is this bad??? She tells us she's tring to lose wight even though she knows we (me and family) won't agree so it's like its for attention or something. Meanwhile while I'm trying to gain gain gain she's trying to lose and i know this might not be fair but it just annoys me!! She should be so greatful to have a healthy weight with CF and not have the possibility of a g-tube lurking at every clinic visit. im worried that if she gets sick she'll just lose wight then get even sicker. Will losing affect her in the long - term??? She has a healthy BMI, 22.5, yet i know CFers should aim to be like 23 or 24 or somthing. What should I do??? She won't listen.