How to GAIN weight?

I've been taking adderall for several months now, and my weight has dropped significantly. I'm 6'1". I was like 185-190 pounds when I began taking it, I believe, and I'm now at probably about 155 pounds. I have seen a decrease in the rate at which I'm losing weight, but I'm still losing it, and before long I'm going to be at unhealthy levels.

At first, I had a lot of trouble getting myself to eat, because it kills my appetite. I've managed to deal with that pretty well, so now I eat probably as much as I did before I started taking adderall. However, it seems as though I lose weight regardless of how much I eat, even if slower.

Naturally, I could just eat a tub of ice cream every day and gain weight, but I would prefer to gain weight in a way that isn't so unhealthy. Are there foods that will help me gain weight without clogging my arteries?