You need to eat fats -- good fats are necessary for a healthy body. But you also need to avoid some fats: the bad fats that raise your cholesterol and increase inflammation. This week, I'll teach you about dietary fats and give you some tips on getting more good fats (and fewer bad fats) into your diet.
First, a Little Chemistry
Fats are made up of individual molecules called fatty acids, which are chains of carbon atoms along with some oxygen and hydrogen atoms. The carbon atoms in the fatty acid molecules are linked by single or double bonds.Fatty acids vary in length. Short chain fatty acids have two to four carbon atoms, medium chain fatty acids have six to 12 carbons atoms, long fatty acids have 14 to 18 carbon atoms. A few fatty acids have more than 20 carbon atoms chains.
Fatty acids are either saturated or unsaturated. Saturated fatty acids have no double bonds between any of the carbon atoms in the chain. Saturated fatty acids are solid at room temperature (think of the fat on red meat). Unsaturated fatty acids have one or more double bonds in the carbon chain. Monounsaturated fatty acids have one double bond and polyunsaturated fatty acids have two or more double bonds. Unsaturated fatty acids are sometimes named by the position of the double bonds in the carbon chain. The names omega-3, -6 or -9 refer to the locations of the first double bond in the the three different fatty acid molecules. The monounsaturated and polyunsaturated fatty acids are liquid at room temperature (think of vegetable oil).
Unsaturated fatty acids can have two different configurations of the hydrogen atoms that are located on either side of the double bonds. These are referred to as "cis" or "trans" configurations. Cis configurations have those hydrogen atoms both on the same side of the molecule. This causes the molecule to look like it is bent. Trans configurations have those hydrogen atoms on opposite sides of the double bond. This gives the molecule a more linear appearance, like saturated fats.
Fats (and cholesterol -- a type of fatty substance that is mostly made by your liver, but some comes from your diet) have a number of important functions, which include:
- Lubrication of body surfaces
- Components of cell membrane structures
- Formation of steroid hormones
- Energy storage
- Insulation from cold
- Carrying fat soluble vitamins A, D, E, K
Good Fats and Bad Fats
But some fats are better for your health than others. The polyunsaturated and monounsaturated fatty acids are generally good, and the saturated fats are bad. The largest amounts of polyunsaturated fats are found in plants, such as in seeds, nuts and vegetable oils. Fish and seafood are also rich in polyunsaturated fats. Olive oil, canola oil, avocado and nuts also contain monounsaturated fatty acids, which are good for your heart and your blood vessels.The bad fats included saturated fatty acids and trans-fats. People who eat large amounts of saturated fats from red meats tend to have higher cholesterol levels, more inflammation and are at a higher risk of cardiovascular disease. Trans-fats may even be worse. Most trans-fats are formed when hydrogen is forced into liquid vegetable oils to make them semi-solid. Some types of stick margarine contain large amounts of trans-fats and some highly processed foods have trans-fats. Some naturally occurring trans-fats are in dairy products; however, they don't seem to be as detrimental as the trans-fats that are created artificially.
Eating a healthy diet means you need to eat fewer trans-fats and saturated fats and more of the polyunsaturated and monounsaturated fats. This week you're going to work on both.
The United States Department of Agriculture suggests that about 30 percent of your calories come from fats, but many people eat much more fat than that. You can start by choosing low-fat and non-fat foods at the grocery store and by choosing recipes that are low in fat (our Guide to Low Fat Cooking has lots of recipes and ideas), generally, you should:
- Cut back on creamy sauces and oily dressings.
- Avoid fried foods.
- Stay away from highly processed foods (or at least read the labels to choose the products with the least amount of total fat).
- Don't eat rich desserts that are high in sugar and fat.
- Use non-stick cookware and non-stick cooking spray instead of butter and oils.
- Choose baked chips and snacks that are lower in fat than regular chips.
