I've found that my weight creeps up if I eat cheese. I really love cheese, its really easy to over eat it, and it packs a lot of calories. Same thing for me with nuts. If I start eating either my weight will start to go up.
Now ice cream, that's another matter entirely. I've seen my weight jump up if I indulge in some ice cream. Like more than you'd think possible in such a short amount of time.
It's frustrating that I see folks eating this stuff and it doesn't seem to be a problem. But I was super heavy (>300 lbs) so it's real easy for me to put on weight.
My suggestion is to try cutting out dairy for a while and see if that helps.