Fat often gets a bad rap. In the 1980s and ’90s, low-fat diets were touted as a cure-all for combating obesity and maintaining heart health (1). Media and health professionals began to evangelize this type of diet and many American consumers started looking for low-fat foods. But just because something is labeled as low-fat doesn’t mean it’s healthy.
“Low-fat diets can be useful, but as with any diet, it needs to be well-planned,” says Becky Kerkenbush, a clinical dietitian and member of the Wisconsin Academy of Nutrition and Dietetics. “Low-fat does not equal low-calorie or healthy. When fat is removed from food, it is often replaced with sugar or sodium.”
But recent studies show that not all dietary fats are created equal and that some fats may actually be beneficial for overall health and wellness (2). “Fat is essential because it plays a role in many body functions.” says Jennifer Kanikua, a registered dietitian and author of The SoFull Traveler. “The key thing is to choose healthy fats and to consume them in healthy amounts.”
Good Fats vs. Bad Fats
There are four main types of dietary fats—trans fats, saturated fats, monounsaturated fats, and polyunsaturated fats—and some of them are better for you than others. Each type of fat has a different chemical structure, says Katrina Trisko, a registered dietitian based in New York.
“Saturated fats remain solid at room temperature, but unsaturated fats remain in a liquid state over a broad range of temperatures. For example, butter, a saturated fat, is a solid at room temperature, but olive oil, an unsaturated fat, remains a liquid even at colder temperatures in the fridge,” she says. “This difference in chemical structure affects how these fats are digested and processed in our bodies.”
Trans fats and saturated fats are considered bad fats by most health professionals. Saturated fats lead to high LDL cholesterol, Kerkenbush says, which increases the risk of heart attack, stroke and some cancers.
“Be conscious of your intake of foods such as processed meats, red meat and dairy products, as these are packed with saturated fats,” Trisko adds.
But other fats in the monounsaturated and polyunsaturated categories are actually beneficial to overall health and wellness. “Omega-3 and omega-6 fatty acids are polyunsaturated fats that can lower triglyceride levels and reduce blood pressure,” Kerkenbush says. “Omega-7 and omega-9 fatty acids are monounsaturated fats that may reduce inflammation, decrease LDL cholesterol and improve insulin resistance.”
Kerkenbush says that foods like lake trout, albacore tuna, salmon, walnuts, flax seeds, chia seeds and canola oil are good sources of polyunsaturated fats, while avocado, olives, olive oil, canola oil and most nuts are good sources of monounsaturated fats.
Common Fat Myths You Shouldn’t Believe
While modern-day research shows that eating healthy fats can have a positive impact on health, there are still a lot of misconceptions surrounding fat in food. We asked our experts to debunk some of these commonly held myths.
Myth 1: All Fats Are Created Equal
As demonstrated above, there are different types of fats and not all of them are bad. So instead of lumping fat into one category and trying to avoid it completely, it’s important to make decisions so that you’re eating the right types of fats instead of the wrong types of fats.
“Fat adds a unique flavor and texture profile and will help you absorb nutrients,” says Kanikua. “Fat is necessary for the body—so our job is to choose the healthy ones.”
Myth 2: All Saturated Fat Is Bad
Most health experts agree that it’s best to avoid saturated fats. But recent studies suggest that some saturated fats like medium-chain triglycerides or medium-chain fatty acids—called MCTs—can be beneficial to brain health (3) and can help increase endurance (4). MCTs are commonly found in foods such as coconut oil, palm kernel oil, cheeses and whole-milk yogurt.
“Saturated fats are not as bad as previously thought, but aren’t protective of our heart health like unsaturated fats,” Trisko says. “You’re better off eating these types of fats in moderation.”
Myth 3: High-Fat Foods Will Raise Your Cholesterol
If your diet mainly consists of processed trans fats and unhealthy saturated fats, you are at risk of raising your cholesterol. But eating a diet high in polyunsaturated and monounsaturated fats can actually have the opposite effect. In fact, Harvard Medical School backs up Kerkenbush’s earlier statements about how eating polyunsaturated fats can lower bad cholesterol (LDL) levels and decrease triglyceride levels (5).
And when it comes to cholesterol, there are other factors at play. “Cholesterol levels are highly linked to genetics—which means some individuals are at risk for having high cholesterol regardless of the foods that they eat,” Trisko says. “So if high cholesterol levels are a concern, don’t jump to conclusions and blame the steak that you ate last week, because that’s likely not the culprit.”
Myth 4: Eating Fat Will Make You Fat
Some people are under the impression that eating fat will make you fat. And while it’s true that fats have a higher calorie density than proteins and carbohydrates, gaining weight is not only caused by eating dietary fats—especially if they are good fats.
“Simply eating fat in your diet will not make you fat,” Trisko says. “Our body weight and body fat distribution is determined by our genetics, overall physical activity and caloric intake. The more excess calories we eat, the more energy our body will store in the form of fat—regardless of what macronutrient those calories came from.”
Myth 5: Fats Don’t Have Any Benefits
It’s easy to think about dietary fat as a harmful ingredient that serves no purpose. But, as mentioned above, good fats actually do a lot for our overall health. “Fat is essential for the digestion, absorption and transport of fat-soluble vitamins, the support of cell growth and hormone production, and the provision of energy,” Kerkenbush says.
Fats will also help you feel fuller longer, Kanikua adds. “Having some fat with your food items not only can help absorb some nutrients, but will help slow down digestion, therefore aiding in long-term satiety.”