Fats: the good, the bad & the ugly

Whether you actively follow nutrition blogs, tune in to a talk show on weekdays, or just browse the wellness section of the newspaper, chances are you have heard a lot about fat lately. Fat is the one of the hottest nutrition buzzwords as of late, and for good reason! Information on this important macronutrient is growing, but questions still remain.

Is saturated fat actually bad for us? What foods have the most omega-3s?

It’s easy to be confused, so let’s take a look at the facts.

First, why is there so much conflicting research? 

If you are like me and grew up during the transition to low-fat everything, you are familiar with the idea that eating too much fat, especially the saturated kind, leads to heart disease, obesity, and a slew of other health problems. However, science tells us that this age-old belief is not necessarily true, and that fat is misunderstood. The benefits and dangers of fat depend on the type and amount you eat. While the majority of fat we eat should come from unsaturated sources, certain types of saturated fat might also have advantages and should not be avoided.

So, how did the “fat is bad” myth evolve? Unfortunately, it is very difficult to make conclusions about causation in nutrition research. Often, the best we can do is correlate certain dietary factors with health benefits or risks, and even then, associations can be weak. For example, if researchers want to examine the effect of blueberry consumption on cancer risk, but do not regulate the participants’ other dietary choices, or consider age, physical activity, smoking, or related lifestyle factors, they cannot make a strong conclusion that blueberries provide unique protection against cancer. Nutrition studies differ in study designs and populations, and many are limited by reports from participants. Recalling the amount and types of foods you ate over a 24 hour period, or 7 days, can be a difficult task. Not to mention that food choices change from day to day; one day is hardly an accurate depiction of someone’s overall diet. Simply put- it’s complicated! That being said, nutrition research still provides valuable information, especially when studies are well-designed. For more details about deciphering correlations and causations for nutrition recommendations, click here.

Many of the studies that linked fat, especially saturated, with heart disease were flawed, as reported by reviews in the American Journal of Clinical Nutrition (1, 2). However, this does not mean that some of the warnings about saturated fat are not true. Again, type and amount matters!

The Role of Cholesterol

The influence of fats on heart disease risk depends on how these fats impact cholesterol levels in the body. Cholesterol can be made up of low-density lipoproteins (LDL) or high-density lipoproteins (HDL). LDL cholesterol, specifically that made up of small and dense particles (instead of large and fluffy ones), is linked to a higher risk of heart disease, while HDL cholesterol is linked to a lower risk (3, 4).

Some research suggests that saturated fat raises LDL cholesterol, contributing to heart diseases, while other studies indicate that saturated fat changes small LDL particles to the beneficial large ones, while slightly raising HDL cholesterol (5, 6). Still more research highlights that saturated fats with long fatty acid chains raise LDL, while saturated fats with short or medium fatty acid chains do not (57, 8). Finally, additional studies detail that the ratios of HDL to LDL, and total cholesterol to HDL, may be more indicative of heart disease risk than levels of just LDL cholesterol (9).

So where does that leave us? While studies on saturated fat suggest that it is not as much of an enemy as we once thought, more research is needed to substantiate this conclusion. Until then, eating certain types of saturated fat in moderation seems to be the best bet, with the added possibility of some health benefits. This means incorporating grass-fed meat, whole milk dairy products, and fats with medium-chain triglycerides, such as coconut oil, in moderation, while limiting saturated fats from highly processed dairy and luncheon meats. After all, products from humanely raised animals in their natural habitats offers a much different nutrient profile than a fast-food cheeseburger.

Lastly, replacing saturated fat in our diets with healthy fats (especially omega-3 PUFA, see below), as opposed to refined carbohydrates and sugar, is also a key factor in reducing our risk of heart disease and related issues (10, 11). Perhaps saturated fat does not have a negative influence in the absence of other inflammatory foods.

Types of Fats

Types of fats include saturated, monounsaturated, polyunsaturated, and trans. Fats in a specific category also differ from each other, depending on their fatty acid composition. This is where it gets complicated. Let’s break it down.

  1. Saturated fats– found in meat and whole milk products, and coconut and palm oils
  2. Monounsaturated fats (MUFA)– found in olives (and olive oil), avocados, nuts (especially pecans and almonds), and seeds; also meat and whole milk products
  3. Polyunsaturated fats (PUFA)– made up of omega-3 fatty acids (EPA, DHA, and ALA) and omega-6 fatty acids
    • Omega-3 fatty acids– found in salmon, mackerel, fish oils, egg yolks, grass-fed bison, walnuts, chia seeds, flax seeds
      • Omega-3 is present in the ALA form in walnuts, chia, and flax. ALA provides many health benefits, but humans have a hard time converting this form to the forms of EPA and DHA. It’s important to consume all 3 of these forms.
    • Omega-6 fatty acids- found in vegetable oils (safflower, soy, cottonseed, corn), nuts and seeds (pumpkin and sesame); also in some types of meats
    • Omega-6 fatty acids tend to have a pro-inflammatory effect in the body, while omega-3 fatty acids have an anti-inflammatory effect. While both are vital for certain bodily functions, the excessive intake of omega-6 is linked to hazardous health effects.
  4. Trans fat– created by the food industry to improve shelf life of products, also called hydrogenated oil; found in processed baked goods, fried foods, and frozen pizzas

What Fats Should We Eat? The Good, Bad & Ugly

Based on current research, the majority of fats in our diet should be unsaturated, with some exceptions.

  1. Good: all types of MUFA and omega-3 PUFA, moderate amounts of omega-6 PUFA, (such as nuts and seeds, but not vegetable oils- more on that later), and moderate amounts of saturated fat from organic, pasture-raised, and/or grass-fed animal products, and coconut oil
    * Good fats are vital for absorbing fat-soluble vitamins, such as Vitamins A, D, E, and K
  2. Bad: excessive amounts of saturated fats, especially those from processed meats and dairy products, in combination with heavy consumption of sugar and refined carbohydrates
  3. Ugly: trans fats, omega-6 heavy vegetable oils
    • Trans fats wreak havoc on your cardiovascular health. They lower HDL cholesterol and raise LDL cholesterol, and  may increase inflammation (12).
    • Although this may come as a shock, vegetable oils, such as safflower, soy, or corn, may be detrimental to our health due to their high omega-6 profiles. They are rampant in processed foods, from salad dressings to potato chips, causing us to consume an excessive amount of omega-6 fatty acids, often without sufficient omega-3 consumption. This may lead to inflammation in the body, as well as the oxidation of LDL cholesterol particles (13). Read more about the dangers of increased omega-6 consumption, in relation to decreased omega-3 intake.


While the research on all types of fats is far from perfect, careful interpretation of available studies, as well as advice from trusted health professionals, is helpful in choosing the best types of fat. Remember, fat is good! It’s the type and quantity that matters.