Which Fats are Good and Bad?

Which Fats are Good and Bad?

Video | Saturated vs. Unsaturated | Saturated Fats (Pros & Cons) | Monounsaturated Fats (Pros & Cons) | Polyunsaturated Fats (Pros & Cons) | Takeaway

For most people, going on a low carb diet really means going on a low-carb/high-fat diet. But just like there are good and bad carbohydrates, there are good and bad fats. Our ideas on which fats are healthy and which are not has changed quite a bit over the years. In this post, I’ll go into the differences, so you know which ones to choose.

Good and Bad Fats Summary

  • We can no longer draw a line and state that all saturated fats are bad, while unsaturated fats are good. 
  • Saturated fats are stable molecules, making them suitable for cooking (i.e. butter, coconut oil, lard, tallow)
  • Saturated and monounsaturated fats are found in many whole unprocessed foods that provide hunger satisfaction and additional nutrients (i.e. vitamins, minerals, protein)
  • Saturated fats may raise LDL cholesterol, and how your body handles a diet high in saturated fats may be determined by your genes. 
  • Research supports the fact that monounsaturated fats are heart-healthy. 
  • Monounsaturated and polyunsaturated fatty acids lack some stability and can breakdown when exposed to elements like heat and light, making them unhealthy to consume. 
  • Polyunsaturated vegetable oils breakdown in the presence of heat and should not be used for cooking.
  • Vegetable oils can be hydrogenated, creating trans fats. 

Which Fats are Good and Bad? [Video]

In this video, you’ll learn…

  • Which fats you should add to your diet!
  • The pros and cons of Saturated Fats, Monounsaturated Fats, and Polyunsaturated Fats.
  • Additional resources for continued weight loss success.

It’s Not Just Saturated vs. Unsaturated

In past decades, we simply drew a line when it came down to deciding if a dietary fat was good for you or bad for you. On one side of the line, we had saturated fats, which were deemed to be unhealthy. On the other side, we had unsaturated fats that were widely regarded as healthy choices. 

We went along with that belief for many years, but then some problems started to arise that blurred the line between what we had thought to be good and bad fats. For instance, coconut oil is mainly composed of saturated fatty acids.

However, it is particularly high in a special type of fatty acid known as lauric acid.

Lauric acid has been shown to significantly increase high-density lipoproteins or HDLs, which we think of as the good cholesterol (1).

Despite the fact that we’ve been trained to think that eating saturated fat increases your risk of cardiovascular disease, here we have a saturated fat that has a protective effect.

There is also a growing body of research that is furthering this idea that saturated fats are not the direct path to heart disease that they were once thought to be (2).

It is OK to Eat Cholesterol

With the health of saturated fats coming into question, the finger was then pointed at cholesterol in our diets. This was when the egg became Enemy Number One because the yolk of an egg contains quite a bit of cholesterol. In fact, there is about 186mg of cholesterol in a large egg making it one of the highest cholesterol foods (source ~Cronometer).

However, the cholesterol that we eat does not significantly affect the level of cholesterol in the blood (3).

If fact, if you are running low on cholesterol, your liver will make it because you need it to make things like cell membranes, bile acids for digestion, hormones, and vitamin D (4).

Not All Unsaturated Fats are Healthy

If we shift gears and look at the other side of the line, we have unsaturated fats that had enjoyed the label of being healthy for many years. However, some problems have started to show up and bring this label into question. 

For instance, polyunsaturated vegetable oils were once heralded as being heart healthy. However, many of these refined oils are high in inflammatory omega-6 fatty acids and extracted using harmful chemicals or heat that causes them to degrade. When we consume them, they create inflammation and degrade cholesterol, making heart disease more likely (5).

While we can’t just flip flop the recommendation entirely and now say that a diet high in saturated fat and low in unsaturated fats is the way to go. These facts show us that the dividing line between good and bad fats is more complex than we had originally thought. 

Let’s dig a little deeper and go into the pros and cons of saturated and unsaturated fats and give some examples of each, so you have a good roadmap. 

Pros of Saturated Fats


One of the best features of saturated fats is that they are very stable molecules. Being saturated means that the bonds of the molecule are all taken up, so there are no available bonds in which a spare oxygen or hydrogen atom could invade the molecule and change it.

That stability makes saturated fats great for cooking. Examples of good cooking fats include butter, coconut oil, and what you might think of as old-fashioned fats like lard and tallow. 

Saturated Fatty Acid

Whole Food Sources

Another pro of saturated fats is that they tend to be found in whole, unprocessed foods. This has two distinct benefits.

First, we get a full range of vitamins and minerals as well as protein from these foods. Second, consuming these fatty foods takes away hunger. Even though gram for gram fat is calorie-dense, we tend to eat less when we eat a low-carb/high-fat/moderate-protein diet (6) (7)

Examples of whole, unprocessed foods that have health benefits despite also containing a significant amount of saturated fatty acids are eggs, high-quality meats, and full-fat dairy products such as yogurt, heavy cream, and varieties of cheese. 

Healthy Saturated Fats

Processed Meat and Dairy

Saturated fats are also found in processed meats like hot dogs, lunch meats, bacon, and low-quality meats from fast-food restaurants as well as dairy treats like ice cream.

While a small amount of these foods will not derail your health, they are not healthy to rely on as a staple of your diet. A diet high in processed foods can increase your risk of chronic diseases like cancer, heart disease, and diabetes (8) (9)

The adage holds true that you cannot outrun the effects of a poor diet.

Cons of Saturated Fats

The Saturated Fat Debate

Despite the pros mentioned above, saturated fats have not enjoyed a fully clean bill of health. For one thing, the health value of a diet high in saturated fats is still a hotly debated topic in the scientific world.

With sources showing that a diet high in saturated fat may raise LDL cholesterol levels. However, it is not clear how much this impacts a person’s risk of cardiovascular disease (10).

Saturate Fats and Genetics

How much saturated fat you can tolerate in your diet may come down to your genes. For some, a diet high in saturated fats may have health consequences.

This vulnerability can be predicted thanks to something called SNPs or single nucleotide polymorphisms, which are variations in your genes that are unique to you. SNPs are useful because certain ones are associated with certain health conditions, and many of them can be turned on or off based on environmental factors like the foods we eat.

For instance, the FTO Gene is nicknamed the Obesity Gene. If this gene variation is present in you, you have a higher risk of obesity, especially if your diet is high in saturated fat. There are other SNPs as well (i.e., PPARG, rs5082) that, if present inside of you, can increase your risk of obesity, diabetes, or heart disease when you follow a high-saturated fat diet. 

Discover Your Genetic SNPs

To uncover gene variations that you might have, perform the following steps: 

1. Go to 23andMe link https://www.23andme.com/

2. Order the basic Ancestry + Traits Service 

3. When you get your 23andMe results, go on their website and download the text file (.txt) or data file (.csv) that contains your information. 

4. Go to the FoundMyFitness website and upload your file to run the comprehensive report. 

You will receive a report that explains risk factors and dietary recommendations that are unique to you. 

Unsaturated Fats: Mono vs Poly

An unsaturated fat can be either monounsaturated or polyunsaturated. The difference has to do with chemistry. As we learned, in a saturated fatty acid, all of the bonds between carbons are single bonds.

Unsaturated fats have one or more double bonds. Mono means one, so in a monounsaturated fat, we have one double bond between carbon atoms. Poly means many, so we have two or more double bonds in those molecules. Let’s look at these fats separately. 

Polyunsaturateted fatty acid vs monounsaturated fatty acid

Pros of Monounsaturated Fats 

Whole Food Source

Like many saturated fats, monounsaturated fats can be obtained from eating whole, unprocessed foods, like avocados, nuts, seeds, and fatty fish. We are getting the hunger satisfaction and health benefits from the fats as well as a host of healthy micronutrients. 

healthy monounsaturated fats

Additional Health Benefits

Monounsaturated fats are also obtained from some healthy oils like olive oil and avocado oil. Regardless of whether the source is a whole food or oil, there is a good body of research to support the fact that monounsaturated fats are heart-healthy (11).

Cons of Monounsaturated fats

Monounsaturated Fats are Less Stable than Saturated Fats

Monounsaturated fats are the ones that we tend to celebrate when it comes to health. However, the double bonds in their structure reveal a vulnerability.

Having a double bond in its chemical structure is kind of like having the two carbons shaking both hands with each other, which is awkward. So, these molecules are less stable and are looking for a free atom to grab onto like an oxygen atom.

This lack of stability is enhanced when the fatty molecules are exposed to elements like light and heat. If this oxidation happens, it changes the oil in ways we don’t want. For instance, oxidation can cause the oil to lose antioxidants and release oxidation products like free radicals that damage cells.

If you’ve noticed, good quality brands of oil are sold in dark bottles to reduce the impact of light. Cooking introduces heat, which can break down monounsaturated oils. 

Extracting Oil and Heat Tolerance

The heat tolerance of oil may have to do with its level of quality. Extra virgin means that the oil was extracted first, which means it contains more antioxidants and helpful compounds than regular olive oil.

The oil is also squeezed out of the plant, and the way that is done affects the quality. You will be best off if you find oils that say “cold-pressed” or “expeller-pressed” because they are extracted without heat or chemicals. 

As for specific monounsaturated oils, avocado oil has a higher smoke point than olive oil, so I use it for cooking along with the saturated fats mentioned earlier. I personally do not use olive oil for cooking due to its potential to breakdown with heat.

Also, there is controversy surrounding some brands of olive oil that are suspected of being mixed with lesser vegetable oils, making them degrade and become unhealthy. 

Cons of Polyunsaturated Fats

Lack Stability

Vegetable oils are not healthy oils partly because they are polyunsaturated, which means that they have multiple double bonds in their structure that can react with oxygen. Vegetable oils are things like soybean, corn, sunflower, and safflower oil.

They are not easy oils to extract, and often require a lot of heat or a chemical solvent to pull the oil out. This will breakdown the oil and introduce harmful byproducts that you don’t want to ingest. 

As a side note, canola oil is an oil extracted from the rapeseed. It contains a good amount of monounsaturated fat, but it is not an oil that I use due to how it is extracted. If you chose to use it, look for cold-pressed or expeller-pressed varieties.  

Hydrogenated Vegetable Oils (Trans Fats)

Another problem with vegetable oils is that their available bonds allow them to bind to hydrogen through a process known as hydrogenation. Food manufacturers like to hydrogenate vegetable oils because it turns the liquid oil into a solid fat, which greatly increases the shelf-life of a food.

However, your body does not like this because this is where trans fats come from, which are well-known for their health risks. These hydrogenated oils are found in things like Crisco and Margarine, which puts them in the not-good column. 

Pros of Polyunsaturated Fats

Omega-3s: The Healthy Polyunsaturated Fats

The news is not all bad when it comes to polyunsaturated fats, and that is because there is one superstar among them, namely omega-3 fish oil. We don’t cook with this type of oil, but getting these fatty acids into your diet on a regular basis provides you with a baseline protection against disease by reducing inflammation in your body.

You can take Omega-3s in capsule form or get Omega-3 fatty acids from foods like fatty fish, seafood, and nuts and seeds. 

healthy polyunsaturated fats


The bottom line is this when you include healthy fats in your diet they will satisfy your hunger, which will naturally prevent overeating. While genetics may play a role in which fats you choose, most people can enjoy a mix of saturated and unsaturated fats from both plant and animal sources, including meat, fatty fish, eggs, avocados, nuts, seeds, and full-fat dairy products.

As for cooking, butter, coconut oil, and avocado oil work to your advantage along with olive oil for low-heat purposes. The fats to keep out of your diet are vegetable oils and fake fats like Crisco, and margarine. There is a lot to learn, a great place to start is with my 0-1-2-3 strategy. It is already being used by more than 60,000 people!

Thanks for reading and have a great week!


(1) Chinwong, Surarong, Dujrudee Chinwong, and Ampica Mangklabruks. “Daily consumption of virgin coconut oil increases high-density lipoprotein cholesterol levels in healthy volunteers: a randomized crossover trial.” Evidence-Based Complementary and Alternative Medicine 2017 (2017).

(2) De Souza, Russell J., et al. “Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies.” Bmj 351 (2015): h3978.

(3) Fuller, Nicholas R., et al. “The effect of a high-egg diet on cardiovascular risk factors in people with type 2 diabetes: the Diabetes and Egg (DIABEGG) study—a 3-mo randomized controlled trial.” The American journal of clinical nutrition 101.4 (2015): 705-713.

(4) Lecerf, Jean-Michel, and Michel De Lorgeril. “Dietary cholesterol: from physiology to cardiovascular risk.” British Journal of Nutrition 106.1 (2011): 6-14.

(5) Teicholz, Nina. “Exit Trans Fats, Enter Something Worse?” Chapter. In The Big Fat Surprise: Why Butter, Meat, and Cheese Belong in a Healthy Diet, 275–81. New York, NY: Simon & Schuster Paperbacks, 2015. Kindle.

(6) McClernon, F. Joseph, et al. “The effects of a low‐carbohydrate ketogenic diet and a low‐fat diet on mood, hunger, and other self‐reported symptoms.” Obesity 15.1 (2007): 182-182.

(7) Sumithran, P., et al. “Ketosis and appetite-mediating nutrients and hormones after weight loss.” European journal of clinical nutrition 67.7 (2013): 759-764.

(8) Rohrmann, Sabine, et al. “Meat consumption and mortality-results from the European Prospective Investigation into Cancer and Nutrition.” BMC medicine 11.1 (2013): 63.

(9) Micha, Renata, Sarah K. Wallace, and Dariush Mozaffarian. “Response to Letter Regarding Article,“Red and Processed Meat Consumption and Risk of Incident Coronary Heart Disease, Stroke, and Diabetes Mellitus: A Systematic Review and Meta-Analysis”.” Circulation 123.3 (2011): e17-e17.

(10) Chiu, Sally, Paul T. Williams, and Ronald M. Krauss. “Effects of a very high saturated fat diet on LDL particles in adults with atherogenic dyslipidemia: A randomized controlled trial.” PloS one 12.2 (2017): e0170664.

(11) Schwingshackl, Lukas, and Georg Hoffmann. “Monounsaturated fatty acids and risk of cardiovascular disease: synopsis of the evidence available from systematic reviews and meta-analyses.” Nutrients 4.12 (2012): 1989-2007.

About the Author

Becky Gillaspy, DC graduated Summa Cum Laude with research honors from Palmer College of Chiropractic in 1991.

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