My height is 172 cm and my weight is only 52 kg. My BMI shows i'm underweight. It say's i need to reach at least 19 or 20(BMI). By birth itself i was suffering from muco visidosis, later told as cystic fibrosis. I'm still taking medicines starting from my childhood. I need to put on some weight , at least average weight. can you help me out in this regard. What sort of foods should i take to gain weight.And what are the ways to clear out my lungs from mucous. It is also seen that the life expectancy of the people having cystic fibrosis is at an average of 37 years of age. I came to know this from different websites featuring about cystic fibrosis with all types of survey results regarding cystic fibrosis. Please give me your valuable advice.