Despite the unfounded gibberish that antiquated diet culture tried to tell us, we know now that fat is both necessary for optimal health and has significant health benefits to offer. "Fat is an essential part of the diet and needs to be eaten every day," explains Carolyn Raikhlin, RD, MBA, MAN, Head of Nutrition Upfield North America. "In fact, about 10 to 35 percent of your calories should come from fat. It protects our organs, helps us absorb certain vitamins, and is part of every cell membrane in the body."
That being said, both the amount and type of fat you consume are key in determining whether or not the foods you eat on a daily basis have a positive or negative effect on your overall health. "Some types of fat, like saturated and trans fat, can raise blood cholesterol levels. Other types of fat, like mono- and polyunsaturated fat, can actually help lower blood cholesterol levels," explains Raikhlin. "And keeping blood cholesterol under control is a key factor in reducing your risk of heart disease and stroke."
Here are the four main types of dietary fats ranked from healthiest to least healthy, according to Raikhlin. We'll also outline what foods are packed with each one and (best of all) how to eat more of the "good" and less of the "bad."
As a rule of thumb, remember that healthy fats typically come from vegetables, nuts, seeds, and fish, and that they're liquid—not solid—at room temperature.
According to Raikhlin, polyunsaturated fats are essential fats, which means they're necessary for normal body functions but that your body cannot make them. Translation? You must get them from food. "Polyunsaturated fats are needed for blood clotting, muscle movement, and inflammation," she explains. "They help build cell membranes and the covering of nerves."
The two main types of polyunsaturated fats are omega-3 fatty acids and omega-6 fatty acids. Good sources of omega-3 fatty acids include fatty fish (think salmon, mackerel, and sardines), walnuts, flaxseeds, canola oil, and non-hydrogenated soybean oil. Foods rich in omega-6 fatty acids include a number of vegetable oils, like safflower, soybean, sunflower, walnut, and corn oils.
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Olive oil is one of the most prominent, well-known forms of monounsaturated fat thanks to its integral role in the ultra-healthy Mediterranean Diet, which has been linked to lower rates of heart disease. Monounsaturated fats are also found in avocados, canola oil, peanut oil, and most nuts, as well as high-oleic safflower and sunflower oil.
"Saturated fats are known to raise blood cholesterol levels and are found mostly in animal-based products including red meat, whole milk, egg yolks, and other dairy products like cheese," explains Raikhlin. Saturated fat is different from unsaturated fat in that it has no chemical double bonds, which makes it more stable, so it is solid at room temperature. According to Raikhlin, it is best to limit foods containing saturated fat.
The worst type of dietary fat are trans fats, which are a byproduct of a process called hydrogenation that is used to turn healthy oils into solids and prevent them from becoming rancid. Trans fat has no known health benefits and there is no safe level of consumption, which is why it has been officially banned in the United States and many other countries.
"It is best to avoid trans fats entirely," says Raikhlin. "Eating foods rich in trans fats increases your amount of harmful LDL cholesterol and reduces the amount of beneficial HDL cholesterol. They also cause inflammation, which is linked to heart disease, stroke, and other chronic conditions like type 2 diabetes."
Unfortunately, despite the fact that they're banned, foods containing less than 0.5 grams of trans fats per serving are labeled as having 0 grams of trans fats. Therefore, while food companies are reducing the amount of trans fat in their products, a number of foods still contain artificial trans fats. The most common sources of trans fats include commercially-produced cakes, pies, frosting, creamy fillings, fried foods, and cookies made with shortening or hydrogenated fat. Fatty cuts of meat and full-fat dairy may also contain trans fats.
Final word: It is best to choose foods with mono- and polyunsaturated fat, while limiting those containing saturated fat and avoiding trans fat.
Easy Ways to Incorporate More Good Fats Into Our Meals, According to the RD
Start by identifying the key sources of saturated and trans fats in your diet, and consider how you might swap them with monounsaturated and polyunsaturated fats. For instance, if you love buttered toast, try topping it with sliced avocado and a drizzle of olive oil instead. Try exchanging red meat for salmon at least once a week, and serve your pancakes with nut butter instead of your usual side of bacon.
“Increase your intake of omega-3 fats by eating fatty fish (such as salmon or rainbow trout), choose omega-3 enriched eggs and whole-grain breads, and use a soft, non-hydrogenated plant-based spread for cooking, baking, and spreading,” Raikhlin recommends.
To reduce both saturated and trans fat in your diet, Raikhlin says to replace dairy butter, lard, shortening, and hard margarine with vegetable oils and a soft, non-hydrogenated plant-based spread that is low in saturated fat, has no trans fat, and provides a source of omega-3 ALA fat. “For instance, the American Heart Association certifies that I Can’t Believe it’s not Butter!’s plant-based spread contains 70 percent less saturated fat than butter and has 0 grams trans fat per serving, unlike dairy butter that contains 0.5 grams trans fat per serving.”
Choose foods that are low in both saturated and trans fat. Compare labels on similar foods to ensure you are choosing ones with the least saturated and trans fat.
Avoid products with ‘hydrogenated oil’ or ‘shortening’ listed as a main ingredient.