Sammi,
I think the weight factor is very important in transplant. The stats show that if you are in your ideal BMI - body mass index that you have better survival numbers.
Most likely centers differ on where your weight has to be before listing, and if there is a long wait for lungs, they might list you and then get you to a program to help gain.
I am 5"5 and weighed 100 pounds when I listed for lungs. All they told me is that they wanted me to gain, don't believe they gave me a goal. I was hoping just for 105 if possible. Somehow in the last few months before transplant I gained... I got up to 121, the most I weighed in my life at that point.
There are some medicines out there that help gain weight, be sure to ask about that. Also exercise helps you eat more.
If I can be of any help email me luckylungsforjo@aol.com
Joanne Schum