The Good Fats
Monounsaturated fats (MUFAs) lower total cholesterol and LDL cholesterol (the bad cholesterol) while increasing HDL cholesterol (the good cholesterol). Nuts including peanuts walnuts, almonds and pistachios, avocado, canola and olive oil are high in MUFAs. MUFAs have also been found to help in weight loss, particularly body fat.Polyunsaturated Fats
Polyunsaturated fats also lower total cholesterol and LDL cholesterol. Seafood like salmon and fish oil, as well as corn, soy, safflower and sunflower oils are high in polyunsaturated fats. Omega- 3 fatty acids belong to this group.
The Bad Fats
Saturated fats raise total blood cholesterol as well as LDL cholesterol (the bad cholesterol). Saturated fats are mainly found in animal products such as meat, dairy, eggs and seafood. Some plant foods are also high in saturated fats such as coconut oil, palm oil and palm kernel oil.
Trans fat is the common name for a type of unsaturated fat with trans- isomer fatty acid(s). Trans fats may be monounsaturated or polyunsaturated.
Trans fats are invented as scientists began to "hydrogenate" liquid oils. Partially hydrogenated oils have been used in food for many reasons. Partial hydrogenation increases product shelf life and decreases refrigeration requirements. Because baking often requires semi-solid fats to suspend solids at room temperature, partially hydrogenated oils can replace the animal fats traditionally used by bakers (such as butter and lard). They are also an inexpensive alternative to other semi-solid oils such as palm oil. Because partially hydrogenated plant oils can replace animal fats, the resulting products can be consumed (barring other ingredient and preparation violations) by adherents to Kashrut (kosher) and Halal, as well as by adherents to vegetarianism in Buddhism, ahimsa in Jainism and Hinduism, veganism, and other forms of vegetarianism.
Unlike other dietary fats, trans fats are neither essential nor salubrious.
It's important to know about trans fat because the consumption of trans fats increases one's risk of coronary heart disease by raising levels of "bad" LDL cholesterol and lowering levels of "good" HDL cholesterol. Coronary heart disease is a leading cause of death in the US.
Health authorities worldwide recommend that consumption of trans fat be reduced to trace amounts. Trans fats from partially hydrogenated oils are more deleterious than naturally occurring oils.
Trans fatty acids (or "trans fat") are fats found in foods such as vegetable shortening, some margarines, crackers, candies, baked goods, cookies, snack foods, salad dressings, commercially fried food such as French Fries from some fast food chains, other packaged snacks such as microwaved popcorn.