Fat is a component in food. Some foods, including most fruits and vegetables, have almost no fat. Other foods have plenty of fat. They include nuts, oils, butter, and meats like beef. The name — fat — may make it sound like something you shouldn't eat. But fat is an important part of a healthy diet. And little kids, especially, need a certain amount of fat in their diets so the brain and nervous system develop correctly. That's why toddlers need to drink whole milk, which has more fat, and older kids can drink low-fat or skim milk. Doing the Math. How much fat should you eat?