Just to understand--you need to gain weight but are finding that it is difficult while taking Letrozole? I gather it can decrease appetite in some people but that others gain weight while on it. I'm not totally sure what your concern is--fill me in if you feel like it.
I've been on letrozole for 21 months with no discernible side effects, although I need to have my bone density checked. I have lost some weight in that time but due to other things--probably a combo of stress and increased exercise. My weight is in normal range. And no one looking at me would worry, as I'm still pretty round!