The Science of Obesity: Fats & Cholesterol

For years we heard that a low-fat, low-cholesterol diet would keep us healthy and help us lose weight. And many of us jumped on the bandwagon, eliminating fat and high-cholesterol foods from our diets. Well, unfortunately, we were doing it all wrong.

Instead of eliminating fat completely, we should have been eliminating the bad fats, the fats associated with obesity and heart disease and eating the good fats, the fats that actually help improve blood cholesterol levels. Before we examine the good fats and bad fats, lets talk about cholesterol.

Cholesterol – Its been ingrained into our brains that cholesterol causes heart disease and that we should limit our intake of foods that contain it, but dietary cholesterol is different than blood cholesterol. Cholesterol comes from two places- first, from food such as meat, eggs, and seafood, and second, from our body. Our liver makes this waxy substance and links it to carrier proteins called lipoproteins. These lipoproteins dissolve the cholesterol in blood and carry it to all parts of your body. Our body needs cholesterol to help form cell membranes, some hormones, and Vitamin D.

You may have heard of good and bad cholesterol. Well, high-density lipoproteins (HDL) carry cholesterol from the blood to the liver. The liver processes the cholesterol for elimination from the body. If theres HDL in the blood, then less cholesterol will be deposited in the coronary arteries. Thats why its called good cholesterol.

Low-density lipoproteins (LDL), carry cholesterol from the liver to the rest of the body. When there is too much in the body, it is deposited in the coronary arteries. This is not good. A build-up of cholesterol in our arteries could prevent blood from getting to parts of our heart. That means that our heart wont get the oxygen and nutrients it needs, which could result in heart attack, stroke, or sudden death. So, if your LDL is higher than your HDL, youre at a greater risk for developing heart disease.

It may come as a surprise, but recent studies have shown that the amount of cholesterol in our food is not strongly linked to our blood cholesterol levels. Its the types of fats you eat that affect your blood cholesterol levels.

Bad Fats – There are two fats that you should limit your intake of saturated and trans fats.
Saturated Fats – Saturated fats are mostly animal fats. You find them in meat, whole-milk products, poultry skin, and egg yolks. Coconut oil also has a high amount of saturated fat. Saturated fats raise both the good and bad blood cholesterol.

Trans Fats – Trans fats are produced through hydrogenation, heating oils in the presence of oxygen. Many products contain trans fats because the fats help them maintain a longer shelf life. Margarine also contains a high amount of trans fats. Trans fats are especially dangerous because they lower the good cholesterol, HDL and raise the bad cholesterol, LDL. Unfortunately, most products do not tell you how much trans fat it contains, but you can find out if its in a product by looking at the ingredient list. If the ingredients contain hydrogenated or partially-hydrogenated oils, then it contains trans fats. Fortunately in 2006, manufacturers will be required to list the amount of trans fat in their products on the nutrition labels, so it will be easier for you to find.

Good Fats – Some fats actually improve cholesterol levels.

Polyunsaturated Fats – Polyunsaturated fats are found in sunflower, corn, and soybean oils. These oils contain Omega-6, an essential fatty acid. However, most people get enough Omega-6 in their diet and instead need more Omega-3. Omega-3 is a fatty acid found in fish and walnuts.

Monounsaturated Fats – Monounsaturated fats are found in canola, peanut, and olive oils.

Both types of unsaturated fats decrease the bad cholesterol, LDL and increase the good cholesterol, HDL.

Now, just because the unsaturated fats improve your blood cholesterol levels, you dont have the go-ahead to eat all of the olive oil, butter and nuts you want. Fat of any kind does contain calories, and if youre trying to lose weight, eat fat in moderation, and stay away from saturated fats.

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