In general, yes, this is about portion control, too. What works well for me is to decide, up front, exactly how much I'll be eating, and not eat more unless I truly am hungry. For instance, if my snack is an apple and 2 Tbsp of PB, I don't eat anything else. Does that make sense?
If you do still feel hungry, try having some veggies without much fat, like red pepper and hummus. If I think I'm hungry, I tell myself that I can have some veggies. If I don't want to eat them, I know that it's "head hunger" and not "belly hunger" that's plaguing me and I find some way to distract myself or just sit down and think about what I'm feeling and why I'm wanting to eat.
I've found that with all the veggies, it's pretty easy to have portion control...you get really full (and you get tired of chewing!) so you don't eat as much as you do with the same serving size of carbs.