The Skinny on Dietary Fats

Learn more about which fats can harm and which can help you find a more balanced diet and reduce your cholesterol from nutrition expert Heather Reese.

Dietary fat is often portrayed as a villain - especially when you're talking about weight control. We always hear that you should avoid fat. And the fact that most food manufacturers make fat-free or low-fat versions of your favorite foods only reinforces the notion that fat is bad. However, dietary fat plays an important role in the body. And eating the right kinds of fat, in the right amounts, is actually healthy.

Fats contribute to the flavor, texture, odor and palatability of foods. And it helps you stay full. Dietary fat also aids in the absorption of the fat-soluble vitamins - A, D, E and K. And while the body can manufacture most fats, we rely on fat from food to provide us with the essential fatty acids - linoleic and alpha-linolenic acids. These fatty acids help maintain healthy skin, normal growth and immune function. They also aid in the prevention of many age-related chronic diseases like heart disease and Alzheimer's disease. Other roles that fat plays in the body include:

  • Providing energy

  • Supporting and protecting internal organs

  • Aiding in temperature regulation

  • Lubricating body tissue

Fat is the most concentrated form of energy. It provides 9 calories per gram, more than double the amount of calories from carbohydrates and proteins. While stored fat is the body's largest and most efficient energy source, dietary fat is difficult to metabolize making it the body's least favorite source of fuel.

Dietary Fat and Cholesterol

Fat is the single largest dietary factor in your body's cholesterol levels. I will explain how fat affects cholesterol levels in more detail below. But first let me explain the different types of cholesterol. There are two types: HDL and LDL. A high level of HDL decreases the risk of heart disease while a high level of LDL increases the risk of heart disease. To put it simply you want high levels of HDL and low levels of LDL. To distinguish between the two types of cholesterol I find it helpful to refer to HDL as "healthy cholesterol" and LDL as "lousy cholesterol".

Saturated Fats

Saturated fats are found in meat, poultry, full-fat dairy products and tropical oils. These fats can increase both your total cholesterol and your "lousy cholesterol" levels. The American Heart Association (AHA) recommends that we limit our intake of saturated fats to less than 10 percent of our total daily calories. Sources of saturated fats include:


  • Butter

  • Meat fat

  • Dairy products made from whole milk

  • Chicken and turkey skins

  • Palm and palm kernel oils

  • Coconut oil

  • Cocoa butter

Unsaturated Fats

There are two types of unsaturated fatty acids, monounsaturated and polyunsaturated. Monounsaturated fats reduce total cholesterol levels while maintaining your "healthy cholesterol" levels. This type of fat is a major component of the Mediterranean diet, which has received a lot of press lately. The AHA recommends that 10 to 15 percent of our total daily calories come from monounsaturated fats. They can be found in the following vegetable oils:

  • Canola oil

  • Olive oil

  • Peanut oil

Polyunsaturated fatty acids also help to reduce total cholesterol levels; however, they also lower your "healthy cholesterol" levels. The AHA recommends that we get no more than 10 percent of our total daily calories from polyunsaturated fats. This type of fat is found in nuts and vegetable oils. Sources of polyunsaturated fats include:

  • Corn oil

  • Cottonseed oil

  • Safflower oil

  • Sesame oil

  • Soybean oil

  • Sunflower oil

Trans Fats

Trans fat is not a naturally occurring substance. It is created when hydrogen is added to vegetable oil, which is a liquid, to create a solid substance. Once considered to be a healthy substitute for saturated fat, recent research has proven quite the opposite to be true. Trans fat has been found to raise cholesterol levels, and has been associated with an increased risk of heart disease. It can be found in foods such as vegetable shortening, some margarines, crackers, candies, baked goods, cookies, snack foods, fried foods, salad dressings and many processed foods. To determine whether a food item you are eating contains trans fat look for the following ingredients on the food label:

  • Shortening

  • Hydrogenated vegetable oil

  • Partially hydrogenated vegetable oil