Lots of people are under the impression that peanut butter, nuts and regular cheeses are great sources of protein. It turns out they are not the best when you are trying to lose weight.
Although these foods have some protein, they are mostly fat, so you’d have to consume a bunch of (high-calorie) servings to get enough protein. For example, to get 25g protein (a good amount for one meal) from tuna, chicken or turkey you would need to eat 100-120 calories. To get that much protein from peanut butter or cheese you would have to eat over 500 calories!
That said, there are low-fat and non-fat cheeses (cottage, feta, string) that are good protein sources. Keep the other foods in the “fat” category and enjoy them in small quantities. Remember that a serving of nuts is only 1/4 cup or 1 ounce.