Of course we can say we are lucky we don't have some other awful disease, cancer, heart defects, etc...
We can also say we are lucky every day that we don't die in a car crash, plane crash, earthquake, lightning strike, shark attack, meteor, etc...
Bottom line, you don't tell someone they are lucky for having any kind of disease, condition, or anything else that they themselves do not wish they had or had happen to them, regardless of how miserable you are in your own body/life.
There is no silver lining and there is no "would you rather?" I (we) have a condition that causes tremendous discomfort and in one way or another, will be dealing with it for the rest of my life.
I don't need/want sympathy. But I will not tolerate ignorance and blatant disrepect.
I wouldn't have told her fat A$% that if she was envious of my weight, she should stop stuffing her face, get off the couch more, or perhaps take up bulimia in which case she too could eat whatever she wanted to and not gain weight, even though that it was I was thinking.
Sure it could be worse, everything can.