I take 3 fish oil capsules, eat a handful of mixed nuts, PLUS get at least two tablespoons of flaxseed every single day.
These are all good fats! I have not gained any weight, nor have I lost any though I walk 2 hrs a day and watch what I eat very carefully. I have to take prescription meds, several of which have weight gain listed as a side effect. I figure that's why I have not lost any.
I would not give up the fish oil no matter what its caloric content.
Fat is fat, calorie-wise. It ads to your daily calorie intake. There's probably much more fat contained in a chinese take-out or a side order of large fries than in all the fish oil you take every day. (Just my opinion).