I guess my philosophy is a bit different. Looking at this jar of peanut butter, the serving size is 2 Tbsp (32 grams), and each serving contains 16g of fat, 6g carbs, and 8g protein.
I just ate a Sargento string cheese stick for a quick snack (28g serving size), and while it only had 80 calories, it also only contained 6g of fat, and 8g of protein, the same as the peanut butter. So, if I wasn't concerned with fat, I could eat just over 4 pieces of cheese to get the same calories, but a much higher amount of protein.
My idea is that fat is useless, and putting on weight means building muscle. To do that, you need protein, and so I try to find foods that have a high percentage of calories from protein. Cheese sticks aren't a great example of that, but it's what I had handy. Lean meats, however, are your best friend for protein, period. Basically, I try to stay away from foods that have empty calories (sodas, cookies, candies) and foods that get most of their calories from fat (mayonnaise, salad dressing, oils, chips). Instead of soda, I drink water, because hydration is also essential for a healthy body. Instead of chips or cookies for a snack, I eat fruit. I don't avoid these less-than-healthy foods entirely, as a salad without dressing is kind of boring, but when I do use them, I use them sparingly.