Clearing Up Confusion on Fats
By Kathleen M. Zelman, MPH, RD
Fear of fat affects us all and many people think our weight loss and heart health problems would be solved if we just eliminated fat from our diets. Unfortunately, it's not that simple. We actually need fats, which are an important part of a healthy diet: They provide essential fatty acids, keep our skin soft, deliver fat-soluble vitamins, and are a great source of energizing fuel. But it's easy to get confused about good fats vs. bad fats, how much fat we should eat, margarine vs. butter and the role omega-3 fatty acids play in heart health.
The U.S. Department of Agriculture's 2005 Dietary Guidelines recommend that adults get 20%-35% of their calories from fats. At a minimum, we need at least 10% of our calories to come from fat but most adults get more like 34-40% because fats taste good and are in many of our favorite foods.
Does dietary fat make you fat?
Dietary fat plays a significant role in obesity because fats are calorie-dense, at 9 calories per gram, while carbs and protein have only 4 calories per gram, and alcohol has 7 calories per gram. It's easy to overeat fats because they lurk in so many foods we love: French fries, burgers, processed foods, cakes, cookies, chocolate, ice cream, thick steaks, and cheese.
Choosing the right types of dietary fats to consume is one of the most important factors in helping to reduce the risk of developing heart disease. But while choosing healthier fats may be better for your heart, when it comes to your waistline, all fats have about the same number of calories. And cutting the total fat in your diet not only may help you shed pounds, it may also help you live longer and healthier.
Types of fats: Good and bad
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, may have the greatest impact and 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.
One type of polyunsaturated fat is omega-3 fatty acids, whose potential heart-health benefits have received a lot of attention. 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, "longchain" type of omega-3s. The American Heart Association® recommends eating 2 servings of fatty fish each week.
Plant sources are a good substitute, but they are usually not as effective as fatty fish in decreasing cardiovascular disease. Do keep in mind that your twice-weekly fish should not be deep-fat fried!
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. While monounsaturated fats like olive oil are a good choice for a fat, consuming a serving at every meal is unlikely to slash belly fat.
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 less healthy fats
There are two types of fat that should be eaten in lesser amounts: saturated and trans fatty acids. In fact, trans fats should not be eaten at all. Both can raise cholesterol levels 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 2010 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.
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 that have virtually been removed from our food supply because of the negative media attention. Experts recommend avoiding trans fats yet they still lurk and are used in some 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.
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.
Read labels and make better choices
An effective 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 information to help you make more informed choices. Look for foods that are low in total fat and 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.
Butter vs. margarine
Margarine is made from poly and monounsaturated vegetable oils, so it contains no cholesterol. Butter, on the other hand, is made from animal fat, so it contains cholesterol and saturated fat. But when healthy oils are "hydrogenated" or made into solids, the processing results in the addition of unhealthy trans fats. The harder the fat (think stick margarine), the more trans fats as compared to soft spreads.
Select margarines with the lowest amount of trans fats for a cholesterol-free spread or enjoy a small portion of butter. Always aim to use the least amount of fat, preferably a poly or monounsaturated oil and when it comes to spreads, use it sparingly. Options like whipped butter or yogurt based spreads offer great alternatives.