"Fat" used to be a bad word in nutrition. Years ago, your doctor might have recommended that you limit or avoid fat in your diet to prevent weight gain and health problems like heart disease and diabetes. Now doctors know that all fats aren't bad. In fact, some fats lower your cholesterol level and help keep you healthy.
Fats have many important functions in your body. They:
- Give you energy
- Keep your body warm
- Build cells
- Protect your organs
- Help your body absorb vitamins from foods
- Produce hormones that help your body work properly
The key is to get a good balance of fats and other nutrients in your diet. Eat the healthiest kinds of fats, in the right amounts.
The Difference between Saturated and Unsaturated Fats
The difference between these fats lies in their chemical structure. All fats are made up of a chain of carbon atoms that are linked -- or bonded -- to hydrogen atoms.
- In saturated fats, the carbon atoms are totally covered, or "saturated," with hydrogen atoms. This makes them solid at room temperature.
- In unsaturated fats, fewer hydrogen atoms are bound to carbon atoms. These fats are liquid at room temperature.
A diet rich in saturated fats can drive up total cholesterol, and tip the balance toward more harmful LDL cholesterol, which prompts blockages to form in arteries in the heart and elsewhere in the body. LDL cholesterol increases your risk for heart disease.
You'll find saturated fat in foods like these:
- Red meat -- beef, lamb, pork
- Skin-on chicken and other poultry
- Whole-milk dairy products like milk, cheese, and ice cream
- Palm and coconut oils
There is some controversy in the medical community over saturated fats. Some studies have found no evidence that these fats directly contribute to heart disease. And some types of saturated fat -- like milk -- might be better for you than others -- such as red meat.
In general, the American Heart Association recommends that you get no more than 5% or 6% of your daily calories from saturated fat. So if you eat 2,000 calories a day, limit saturated fat to 120 of those calories or 13 grams of saturated fat per day..
What you replace saturated fat with in your diet also matters. For example, eating polyunsaturated fat instead of saturated fat might lower your heart disease risk. But replacing saturated fats with carbohydrates might increase your heart disease risk.
Small amounts of trans fats are found naturally in animal-based foods like meat and milk. But most trans fats are made in an industrial process. Companies add hydrogen to liquid vegetable oils to make them solid at room temperature. Why do this? Trans fat helps food last longer. It also gives foods a satisfying taste and texture.
You may find trans fats in these foods:
- French fries and other fried foods
- Cakes, pies, biscuits, cookies, crackers, donuts, and other baked goods
- Stick or tub margarines
- Microwave popcorn
- Frozen pizza
Trans fat might taste good, but it's not good for you. This unhealthy type of fat raises your LDL cholesterol level, increasing your risk for heart disease, stroke, and type 2 diabetes, and lowers "good" HDL cholesterol. The American Heart Association recommends that you get no more than 1% of your daily calories from trans fats. Some places -- like New York City -- have banned trans fats altogether.
Unsaturated fats come mainly from vegetables, nuts, and fish. They're liquid at room temperature. Because these fats are good for your heart, and the rest of your body, experts recommend that you eat them in place of saturated and trans fats.
Unsaturated fats come in two forms:
Monounsaturated fats have one unsaturated chemical bond. Oils that contain these fats are liquid at room temperature, but they turn solid when you refrigerate them.
You'll find monounsaturated fats in foods like these:
- Olive, canola, and peanut oils
- Almonds, hazelnuts, pecans, and other nuts
Polyunsaturated fats have many unsaturated chemical bonds. Polyunsaturated oils stay liquid both at room temperature and in the refrigerator.
You'll find polyunsaturated fat in foods like these:
- Flaxseed, corn, soybean, and sunflower oil
- Salmon, tuna, and other fatty fish
There are two types of polyunsaturated fats: omega-3 and omega-6 fatty acids.
Omega-3 fatty acids come in three forms:
- Eicosapentaenoic acid (EPA) -- found mainly in fish
- Docosahexaenoic acid (DHA) -- also found mainly in fish
- Alpha-linolenic acid (ALA) --from plant sources like flaxseed, vegetable oils, and nuts
Studies show that eating fish high in omega-3 fatty acids lowers the risk of cardiovascular disease. Yet taking omega-3 supplements may not have the same benefit. Researchers are also looking at whether omega-3s might help prevent or slow the progress of Alzheimer's disease and other forms of dementia.
You need to get these essential fats from food, because your body doesn't make them. To get enough omega-3 fatty acids in your diet, eat fish like salmon, mackerel, and herring at least 2 times a week.
Omega-6 fatty acids are found in foods like leafy green vegetables, seeds, nuts, and vegetable oils. Doctors used to think omega-6 fatty acids contributed to heart disease. Now, evidence suggests these fatty acids are actually good for your heart.
The American Heart Association recommends that you get 5% to 10% of your daily calories from omega-6 fatty acids. Most people already get this amount in their diet.
The Bottom Line
To keep your heart -- and the rest of you -- healthy, get most of your fats from unsaturated sources. And, get the bulk of your nutrition from healthy foods like vegetables, fruits, whole grains, and lean protein such as fish and skinless poultry.