One of three main categories of basic nutrients (the others are protein and carbohydrates) that are used by the body for energy. Fat has the highest caloric value of all classes of nutrients and is an important energy source for warm-blooded animals. Fat content in foods is made up of saturated and/or unsaturated fats. While both types provide calories, unsaturated fats are much more healthy than saturated fats. Products produced from vegetable fats are generally healthier than products containing animal fat.