(HealthDay)—Even when you’re trying to lose weight, you need some fat in your diet for good health. While fat in general has gotten a bad rap, some types of fat—particularly plant-based fats—are good for you in moderation. Good-for-you fats: Olive, flaxseed oil and other plant-based oils. Fatty fish. Avocados. Walnuts, other nuts and their oils.