Fats, when digested, provide fatty acids which are needed for the proper function of your body.  There are four different types of fat found in food but not all of them are needed by the body.  Essential fats (which mainly come from polyunsaturated and monounsaturated fats) can only be supplied by food.  The main types of fat are:

Monounsaturated fats: come from vegetables, seeds and plants.  They are important in keeping your heart healthy and your immune system functioning.  These fats should be included in the diet regularly: olive oil, canola oil, sunflower oil, cashews, pecans, hazelnuts, macadamias, almonds, avocado.

Polyunsaturated fats: come from vegetables, seeds, plants, fish and fish oils; they are vital for keeping your heart healthy, your immune system working and your brain functioning optimally.  These fats should be included in the diet regularly.  Omega-3 fats (from linseed, fish and fish oil) and Omega-6 fats (from vegetable oils) perform important functions in your immune system.  Examples include sunflower oil, safflower oil, fish and fish oil, linseed and flaxseed oil, soybean oil, sesame oil, most nuts and seeds (e.g. evening primrose oil, walnuts).

Saturated fats: can be used as an energy source in helping cells work, or stored away as body fat.  A small amount is essential (and unavoidable) in the diet.  Examples include cream, milk fat, some dairy fats, some animal fats, lard, copha, ghee, dripping, palm oil, coconut oil.

hydrogenated (trans) fats: are processed fats that cannot be used effectively by the body; they are stored as body fat, raise cholesterol levels and have many other detrimental health effects.  They possibly hinder the immune system and they should be avoided wherever possible.  Examples include hydrogenated vegetable oils (e.g. margarine), potato crisps and other snack foods (e.g. Twisties, Burger Rings), donuts, muffins, pasties, pies, sausage rolls, hot chips, cakes, biscuits and many fast foods