Fat

Fat is the most overconsumed nutrient in most diets. Although it can be important - fat helps your body transport and absorb certain vitamins - much of the fat we eat is unnecessary and is part of our diet simply for the benefits it gives to the taste of foods.
There are several kinds of Fat. The vast majority of fats are in a group known as triglycerides, which is made up of three different types of fatty acids: saturated fat, monounsaturated fat, and polyunsaturated fat. Saturated Fat, which accounts for about 40% of most of the fat we consume, comes primarily from animal fats. It's not needed in your diet at all and it raises the levels of cholesterol in your blood. Mono- and Polyunsaturated Fat, on the other hand, are the only type of fat found in vegetable fats and lower cholesterol levels in your bloodstream. Most recent evidence shows that while you should strive to try and maintain a diet with less than 30% of your calories coming from fat, the unsaturated fats do more good than harm.
A diet high in fat can put you at risk for a variety of problems, such as Heart Disease, Stroke, and several kinds of cancer.