The Skinny on Fat: Good Fats vs. Bad Fats
How fats fit into your healthy diet.
Good Fats vs. Bad Fats
Basically, there are two groups of fats: saturated and unsaturated. Within
each group are several more types of fats.
Let's start with the good guys -- the unsaturated fats. Unsaturated fats
include polyunsaturated fatty acids and monounsaturated fats. Both mono- and
polyunsaturated fats, when eaten in moderation and used to replace saturated or
trans fats, can help lower cholesterol levels and
reduce your risk of heart disease.
Polyunsaturated fats, found mostly in vegetable oils, help lower both blood
cholesterol levels and triglyceride levels -- especially when you substitute
them for saturated fats. One type of polyunsaturated fat is omega-3 fatty
acids, whose potential heart-health benefits have gotten a lot of
Omega-3s are found in fatty fish (salmon, trout, catfish, mackerel), as well
as flaxseed and walnuts. And it's fish that contains the most effective,
"long-chain" type of omega-3s. The American Heart Association
recommends eating 2 servings of fatty fish each week.
"Plant sources are a good substitute for saturated or trans fats, but
they are not as effective as fatty fish in decreasing cardiovascular
disease," notes Lichtenstein. Do keep in mind that your twice-weekly fish
should not be deep-fat fried!
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
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.