Fat

Here we are referring to fat in our diet, not Body Fat. Dietary fat comes in four different varieties: Saturated, Polyunsaturated, Monounsaturated, and Hydrogenated. For practical use, these four can be narrowed down some more into good fats and bad fats.
Saturated and hydrogenated fats are known to clog your coronary arteries making it difficult for blood to get through freely causing all types of heart problems. Unfortunately for us, these are the fats that are easy to come by. Fortunately, they’re also easy to spot.
Hydrogenated fats are liquid oils that have been chemically treated to make them semi-solid, like margarine, and saturated fats are animal fats that come from meat and dairy products.
The good fats on the other hand can actually reduce blood cholesterol levels and protect against heart disease. These can be found in most oils, e.g. Vegetable oil, nut oil, etc.
Fats also contain the fat soluble vitamins A, D, E, and K
One gram of fat contains 9 Kcal of energy.