Although all fats have the same amount of calories, some are more harmful than others: saturated fats and trans fats in particular.
Saturated fatsThese fats are derived from animal products such as meat, dairy and eggs. But they are also found in some plant-based sources such as coconut, palm and palm kernel oils. These fats are solid at room temperature. Saturated fats directly raise total and LDL (bad) cholesterol levels. Conventional advice says to Avoid them as much as possible. More recently, some have questioned this, as there are different kinds of saturated fats, some of which have at least a neutral effect on cholesterol.
Trans Fats or Hydrogenated FatsTrans fats are actually unsaturated fats, but they can raise total and LDL (bad) cholesterol levels while also lowering HDL (good) cholesterol levels. Trans fats are used to extend the shelf life of processed foods, typically cookies, cakes, fries and donuts. Any item that contains “hydrogenated oil” or “partially hydrogenated oil” likely contains trans fats. Hydrogenation is the chemical process that changes liquid oils into solid fats. The tide is turning against trans fats. Since January 2006, all food manufacturers are required to list trans fat content on food labels.
Unsaturated fatsMonounsaturated fats and polyunsaturated fats are two types of unsaturated fatty acids. They are derived from vegetables and plants.
- Monounsaturated fats are liquid at room temperature but begin to solidify at cold temperatures. This type of fat is preferable to other types of fat and can be found in olives, olive oil, nuts, peanut oil, canola oil and avocados. Some studies have shown that these kinds of fats can actually lower LDL (bad) cholesterol and maintain HDL (good) cholesterol.
- Polyunsaturated fats are also liquid at room temperature. These are found in safflower, sesame, corn, cottonseed and soybean oils. This type of fat has also been shown to reduce levels of LDL cholesterol, but too much can also lower your HDL cholesterol.
Omega-3 fatty acidsThese include an “essential” fatty acid, which means it's critical for our health but cannot be manufactured by our bodies. Good sources of omega-3 fatty acids include cold-water fish, flax seed, soy, and walnuts. These fatty acids may reduce the risk of coronary heart disease and also boost our immune systems.
So read those food labels carefully and choose your fats wisely. And as a rule of thumb, liquid fats are better for you than solid fats.