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Good Fats and Bad Fats

The word "fat" is tossed around all over the place. There are good fats, bad fats, fats that make you put on weight, etc. The truth is we talk about fat a lot, but fats have gotten a worse reputation than they deserve. They actually perform very important functions in our body.

Fats protect our internal organs. They help us regulate our body temperature and absorb fat-soluble vitamins (A, D, E and K). They provide essential substances that our bodies cannot produce on their own. One of their most important functions is to act as a fuel reserve. This is why they get stored in our bodies for later use, in case we don’t eat.

Good Fats and Bad Fats


Fat consumption has increased dramatically in the past few years due to changes in eating habits including the high consumption of fried foods and fast food. The U.S. and most Latin American countries’ dietary guides recommend opting for a diet that is relatively low in fats, especially saturated fats and cholesterol.

Fats can be classified into two broad categories: vegetable fats and animal fats. Vegetable fats and fats derived from fish are the most recommended for human consumption.

Fats can also be classified according to their chemical structure: saturated and unsaturated. Unsaturated fats can be further broken down into polyunsaturated and monounsaturated. 

  • Saturated fats, except palm and coconut oil, are hard or solid at room temperature. They can be of animal origin (like lard), or of plant origin (like vegetable shortening), but are generally of animal origin. Saturated fats are the ones that we need to avoid because our livers convert them into cholesterol. High levels of saturated fat intake are associated with increased risk of heart disease.
  • Unsaturated fats are divided into monounsaturated (like canola and olive oil) and polyunsaturated fats (like corn, safflower, sunflower oils, and the popular omega-3 and omega-6 fats found in fish and flax seed oil, respectively). These kinds of fats lower blood cholesterol when they replace saturated fats in our diet. Moreover, fish oil has been associated with a lower risk of heart disease, which is why you should eat fish at least two or three times a week.

Animal fats, on the other hand, contain cholesterol. It accumulates in our arteries and blocks them by forming plaques that can interrupt normal blood flow (atherosclerosis). People talk about "good cholesterol" and "bad cholesterol," but not because they are different. Cholesterol is a fat and can therefore not be transported by itself in our blood. We therefore have special vehicles in our blood called "lipoproteins" which transport cholesterol.

High-density lipoproteins (HDL) are considered "good cholesterol" because they take cholesterol from the arteries to the liver where it is used to produce other substances. Low-density lipoproteins (LDL) are "bad cholesterol" because they transport cholesterol from the liver to the arteries, where they contribute to forming cholesterol plaques. We should be careful and not eat too much animal fat because our body makes cholesterol from the saturated fats we eat. When we lower our fat and cholesterol intake, we can lower our blood cholesterol levels.

"Trans fats" are other fats that have recently been getting attention. These are unsaturated fats found in vegetable shortening, margarines, cookies, desserts, and potato chips, among other foods. These fats are now known to be bad for your health because they help increase the levels of "bad cholesterol" (the one that can block arteries). These fats are formed when vegetable oils are hydrogenated to make them hard (like vegetable shortening) or simply to increase the shelf life of cooking oils.

We have to limit the amount of fried and fatty food we eat. Here’s how:

  • Use moderate amounts of fat.
  • Eat more fruit, vegetables, cereals, and grains.
  • Opt for low-fat dairy products, lean meat (with no fat), chicken without the skin, turkey, and fish. If you buy cuts that have skin, remove all the fat before cooking.
  • Use small amounts of dressing on your salad. Use sparing amounts of mayonnaise, butter, or margarine. Choose fat-free varieties.
  • Use vegetable oil for cooking. Better yet, use spray cooking oil.
  • Season your dishes with fragrant herbs, spices, lemon juice, and fat-free sauces.

Regardless of their origin or whether they are good for you, fats are an excellent, concentrated source of energy (calories), but we have to be careful not to eat too much of them if we want to control our weight.

*Dietitian of the MyDiet™ Team

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