Busting Big Fat Myths

A combination of TV commercials, magazine articles, food packaging, popular diets, and YouTube fitness gurus may shape our relationship with dietary fat. Is fat good now? (Keto evangelists are constantly posting “fat bomb” recipes on Pinterest.) Is fat bad because it makes us fat? Which foods should we invite into our kitchens and which should we pass by without a second glance? The decades-long fat kerfuffle has confused us all. Let’s dispel some myths and determine how much and what kinds of fats will make us feel, look, and perform our best.

What Has Fat Done for You Lately?

Fat is an essential part of your eating plan. Fat adds more than calories to the diet; it’s necessary for energy, muscle movement, absorbing fat-soluble vitamins, building cell membranes, clotting, and reducing inflammation. It also makes up the myelin sheath (the protective layer that covers the brain), which is pretty important.

Big Fat Myth #1: All Fat is Bad

Just like fashion, jokes, and meetings, some types of fat are good and some are bad. There are three types of dietary fat: trans fat, saturated fat, and unsaturated fats (poly- and monounsaturated fatty acids).

Trans Fat

Trans fats are industrially produced through a process called hydrogenation, which makes them shelf-stable and solid at room temperature. Trans fats come disguised as tempting treats like pastries and snack foods. You may like these foods, but they definitely do not like you. If you let them in, trans fats can put you at risk for chronic illnesses including diabetes, coronary artery disease, and metabolic syndrome. These harmful fats may increase total cholesterol in the blood and create inflammation, which is linked to heart disease, stroke, diabetes, arthritis, and other chronic health conditions. (1) If you exclude them from your diet, you will reduce your risk of chronic illness.

Fortunately, in 2015 the Food and Drug Administration (FDA) ruled trans fats unsafe to eat and gave food makers three years to remove them from the food supply. On the other hand, more than three years later, trans fat can still be found in packaged snacks and desserts, as well as some restaurant foods. A few common trans fat food offenders include fried foods, store-bought pie crust, shortening, and nondairy creamers. You can review the nutrition labels on packaged foods and easily identify trans fats, but don’t let “zero grams trans fat” fool you. Companies are allowed to round down and put “0 grams” on the nutrition label if the product has 0.5 grams of trans fat or less.

Saturated Fat

Even experts disagree about the role of saturated fat. Fortunately, most nutritionists do agree that more research is needed. High intake of saturated fat has been correlated with increased incidences of chronic illness like heart disease, but the direct relationship has been blurred depending on the source and frequency of saturated fat consumption.

Common saturated fatty acids include lauric, myristic, palmitic, and stearic acid. (2) Research concludes that lauric, myristic, and palmitic fatty acid consumption raised low-density lipoprotein (LDL) cholesterol, whereas stearic acid was mostly neutral. (2) LDL cholesterol is considered the “bad” cholesterol because a high level of LDL cholesterol in the blood is correlated with heart disease and other illnesses. Lauric and myristic acid is found most commonly in coconut oil, whereas palmitic acid is found in fatty cuts of meat, full-fat dairy, butter, and palm oil. Stearic acid is less common but can be found in fatty cuts of beef, egg yolks, and butter. (3) Eat high-saturated-fat foods from animal and plant sources in moderation or limit saturated fat intake to less than ten percent of your total calories. That’s 20 grams for a 2,000 calories diet. As a reference, 3 ounces of ground beef contains about 8 grams of saturated fat. (3)

Unsaturated Fat

Unsaturated fats, like mono- and polyunsaturated fatty acids, have been deemed “good fat” because of their disease-preventive properties. (4) Unsaturated fats are liquid at room temperature and come from nuts, seeds, fatty fish, and vegetables. The Mediterranean diet, rich in plant-based foods and healthy proteins, revealed the benefit of unsaturated fats. Total fat grams in the Mediterranean diet were similar to the Western diet, but the difference was the type of fats consumed. Mediterranean diet participants experienced low rates of heart disease despite their high-fat diet, due to consuming mostly unsaturated fat. The Western diet tends to be higher in saturated fats.

A diet rich in both types of unsaturated fat has been shown to be beneficial. Polyunsaturated fats are essential fatty acids, meaning they can’t be made by the body even though they are needed for normal bodily functions. There are two types of polyunsaturated fatty acids: omega-6 and omega-3 fatty acids. Both are linked to protection against heart disease and promote increased levels of high-density lipoprotein (HDL) cholesterol, or “good cholesterol.” Omega-6 and omega-3 fatty acids may also help lower levels of LDL cholesterol (“bad cholesterol”) and triglycerides in the blood. (4) The second type of unsaturated fat is calledmonounsaturated fat. Monounsaturated fat is found in avocados, nuts, seeds, and plant-based oils like olive, canola, peanut, and safflower. (5) Similar to polyunsaturated fats, a diet that includes monounsaturated fats can help reduce bad cholesterol and lower your risk of heart disease and stroke.

Big Fat Myth #2: Low-Fat is the Best Choice

Although low-fat crackers or fat-free whipped cream might be enticing, these foods are not a healthy addition to your diet. Low-fat and fat-free foods replicate the natural taste or texture of a full-fat product by adding sugar, salt, flour, or thickeners.

But wait. Which one is worse: fat or added sugar? Should you avoid fat even if it means you’re adding sugar? Or is sugar the bad one? Ultimately, fats—specifically healthy, unsaturated fats—are important because of their role in nutrient absorption and cellular structure. Sugar, on the other hand, is not an essential nutrient. Ultimately, when choosing foods that come in low-fat or full-fat, consider your total calorie needs and how often you would like to include that food in your diet. For example, if yogurt is a daily breakfast and snack food, consider going for the fat-free variety. However, if you consume cheese once or twice a week, allow yourself to enjoy the full-fat variety. The calorie difference is minimal and, in the proper serving size, will not break the bank on your fat allotment for the day.

Big Fat Myth #3: Eating Fat Makes You Fat

How Much Fat Should I eat?

Recommended daily fat intake varies by individual. Refer to your Ixcela daily eating plan, included in your gut health results, for the quantities of fat you should include with each meal, or utilize tools like My Fitness Pal to learn how many calories and how much fat your body needs depending on your goals and physical activity. Then, decide which healthy-fat-containing foods fit your daily eating plan.

Remember, dietary fat does not immediately turn into body fat. Fat is an important macronutrient that, if included in the right portion size from the best sources, benefits a variety of essential processes. Look for foods that contain healthy unsaturated fats that were explained a few paragraphs up, and keep reading for examples of healthy-fat foods to add to your shopping list.

About the Author

Photo: Rachel Stuck, RDN

Registered Dietitian Nutritionist Rachel Stuck has a background in culinary arts and nutrition counseling. Rachel takes a positive approach to nutrition: she avoids recommending restrictive diets and instead focuses on helping people choose foods that promote health and well-being. She is passionate about empowering and assisting Ixcela members as they develop their unique, gut-healthy lifestyles.

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Interested in learning more about Ixcela? Check out Ixcela’s microbiome test, personalized nutrition and fitness plans, and other tools to help you optimize your health.


1. “Trans fatty acids - A risk factor for cardiovascular disease” Pakistan Journal of Medical Sciences vol. 30,1 (2014): 194-7.

2. J.E. Hunter, J. Zhang, Kris-Etherton PM. "Cardiovascular disease risk of dietary steric acid compared with trans, other saturated, and unsaturated fatty acids: a systematic review" American Journal of Clinical Nutrition 2010;91:46-63.

3. Harvard Health Publishing. “The Truth about Fats: the Good, the Bad, and the in-Between.” Harvard Health Blog, Harvard University, 18 Aug. 2018, www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good.

4. Li, Yanping et al. “Saturated Fats Compared With Unsaturated Fats and Sources of Carbohydrates in Relation to Risk of Coronary Heart Disease: A Prospective Cohort Study” Journal of the American College of Cardiology vol. 66,14 (2015): 1538-1548.

5. “Monounsaturated Fat.” About Heart Attacks, 1 June 2015, www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/monounsaturated-fats.