I didn't really gain weight while I was taking meds, it was more like swelling! I was retaining a lot of fluid and literally looked like a balloon, my normal weight is usually between 105 and 110 lbs and during that time I went all the way up to 125 which isn't really bad because some people gain a lot more than that. I tried exercising more than usual but for some reason I wouldn't sweat so my weight wouldn't change. That weight gain is not caused by your diet or because you're not physically active, the truth is, some of those drugs affect your kidney function and make you retain excess water and fat, that is why it is practically impossible to lose that weight for as long as you're taking that substance. I was having a lot of joint and muscle pain along with some other really nasty side effects so I've decided to give up meds completely. One month after I stopped taking that stuff, my weight went right back to normal.