Fats: The Skinny on Fat (cont.)

It is best to get your omega-3s from food, not supplements, Lichtenstein says: "Except for people with established heart disease, there is no data to suggest omega-3 supplements will decrease heart disease risk."

The other "good guy" unsaturated fats are monounsaturated fats, thought to reduce the risk of heart disease. Mediterranean countries consume lots of these -- primarily in the form of olive oil -- and this dietary component is credited with the low levels of heart disease in those countries.

Monounsaturated fats are typically liquid at room temperature but solidify if refrigerated. These heart-healthy fats are typically a good source of the antioxidant vitamin E, a nutrient often lacking in American diets. They can be found in olives; avocados; hazelnuts; almonds; Brazil nuts; cashews; sesame seeds; pumpkin seeds; and olive, canola, and peanut oils.

The 'Bad' Fats in Your Diet

Now on to the bad guys. There are two types of fat that should be eaten sparingly: saturated and trans fatty acids. Both can raise cholesterol levels, clog arteries, and increase the risk for heart disease.

Saturated fats are found in animal products (meat, poultry skin, high-fat dairy, and eggs) and in vegetable fats that are liquid at room temperature, such as coconut and palm oils. The 2005 Dietary Guidelines recommend limiting saturated fats to 10% or less of your total calories, while the American Heart Association recommends keeping them to just 7% of total calories.

Lichtenstein recommends using liquid vegetable oils in place of animal or partially hydrogenated fats.

"There is evidence that saturated fats have an effect on increasing colon and prostate cancer risk, so we recommend whenever possible to choose healthy unsaturated fats -- and always strive to be at a healthy weight," Doyle explains.

We're also hearing a lot these days about trans fatty acids, or trans fats. There are two types of trans fats: the naturally occurring type, found in small amounts in dairy and meat; and the artificial kind that occur when liquid oils are hardened into "partially hydrogenated" fats.

Natural trans fats are not the type of concern, especially if you choose low-fat dairy products and lean meats. The real worry in the American diet is the artificial trans fats. They're used extensively in frying, baked goods, cookies, icings, crackers, packaged snack foods, microwave popcorn, and some margarines.

Some experts think these fats are even more dangerous than saturated fats.

"Trans fats are worse than any other fat, including butter or lard," says Michael Jacobson, executive director of the Center for Science in the Public Interest, a nonprofit advocacy group.

Research has shown that even small amounts of artificial trans fats can increase the risk for heart disease by increasing LDL "bad" cholesterol and decreasing HDL "good" cholesterol. The American Heart Association (AHA) recommends limiting trans fat to less than 2 grams per day, including the naturally occurring trans fats. The U.S. Dietary Guidelines simply recommend keeping trans fats consumption as low as possible.

Still, eliminating trans fats is not a magic bullet, experts say.

"Trans fat is getting lots of bad press, but it is important to keep in mind the 'big fat picture,' which includes lowering total fat, reducing saturated fat, and engaging in an overall healthy lifestyle," cardiologist Robert Eckel, MD, tells WebMD.

Which Fat Is Which?

Most foods contain a combination of fats but are classified according to the dominant fat. This chart lists sources of the good-for-you unsaturated fats as well as some examples of fats you want to avoid.

Saturated Fats or Trans fatty acids Polyunsaturated Fats Monounsaturated Fats
Butter Corn oil Canola oil
Lard Fish oils Almond oil
Meat, lunchmeat Soybean oil Walnut oil
Poultry, poultry skin Safflower oil Olive oil
Coconut products Sesame oil Peanut oil
Palm oil, palm kernel oil and products Cottonseed oil Avocado
Dairy foods (other than skim) Sunflower oil Olives
Partially hydrogenated oils Nuts and seeds Peanut butter

Read Labels and Make Better Choices

The best way to keep on top of the fats in your diet is to become a label reader. On the nutrition facts panel, you'll find all the information you need to make healthful choices. Look for foods that are low in total fat and well as in saturated and trans fats. Bear in mind that a product whose label boasts it is "trans fat free" can actually have up to 0.5 grams of trans fats per serving -- and these can add up quickly.

Here are more tips to help you reduce the total amount of fat in your diet and make sure the fats you consume are the healthy ones:

  • Choose a diet rich in whole grains, fruits, and vegetables.
  • Try a vegetarian meal, with plenty of beans, once a week.
  • Select dairy products that are skim or low-fat.
  • Experiment with light and reduced-fat salad dressings.
  • Replace fattier sauces with vinegars, mustards, and lemon juice.
  • When using fats, do so sparingly. Try to use unsaturated liquid oils, such as canola or olive, instead of butter or partially hydrogenated margarine.
  • Limit your consumption of high-fat foods, such as processed foods, fried foods, sweets, and desserts.
  • When cooking, substitute the lower-fat alternative (for example, low-fat sour cream or low-fat cream cheese) whenever possible

Published October 31, 2007.


SOURCES: WebMD Weight Loss Clinic Expert Column: "The Skinny on Fats." WebMD Weight Loss Clinic Feature: "Trans Fat Free Food: What's the Truth?" Alice H. Lichtenstein, DSc, Gershoff Professor of Nutrition Science and Policy, director and senior scientist, Cardiovascular Nutrition Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University. Robert Eckel, MD, past president, American Heart Association. Michael Jacobson, PhD, executive director, Center for Science in the Public Interest. Colleen Doyle, MS, RD, nutrition and physical activity director, American Cancer Society.

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