Some nutritionists treat oils as a separate category of food. I don’t because oils are almost always used in other foods and are seldom consumed plain, so it’s more practical to focus on the foods they’re used in.
One reason some nutritionists treat oils as a distinct food category is that it helps them to construct a diet with healthy fat guidelines—that is, a diet that includes enough essential fats and not too much saturated fat or total fat. In my view this bottom-up approach (focusing on nutrients instead of foods) is needlessly complicated. You can easily avoid eating too much saturated and total fat without ever thinking about oils per se and instead following my diet quality guidelines. To ensure that you get enough essential fats, take a daily omega-3 fat supplement as described in the preceding chapter.