Our bodies are genetically engineered to crave fat. It’s what keeps us going, keeps us warm, and keeps up our energy levels.While fat does have a lot more calories than the same amount of carbs or protein, it takes a long time to digest fat. It keeps us full and satisfied much longer than any other type of food. Does that mean you should go on a bacon and butter diet with a sprinkle of deep-fried foods? Of course not.