Most plain fruits and vegetables do not contain any fat. Avocados are the exception to the rule, but their fat is monounsaturated, which is a heart-healthy fat. Egg whites and skim milk are fat-free sources of protein.
The human body requires fat to build up its natural insulation and to absorb and transport some vitamins. Fats also play a role in transmitting signals between cells. However, too much dietary fat contributes to obesity. A healthy diet includes no more than 35 percent of its calories from fat and no more than 10 percent of its calories from saturated fats. Fish, olives, seeds and nuts are among the best sources of heart-healthy fats.