Good Fats vs. Bad Fats on the Ketogenic Diet

Dr. Anthony Gustin is a board-certified sports chiropractor, functional medicine practitioner, entrepreneur, podcast host, and founder of Perfect Keto.

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Since they make up around 70% of macros on the ketogenic diet, fats are obviously important. However, the type of fat is really important too, and there can be some confusion about what’s best to consume.

Here’s a breakdown of what fats you should include and which you should avoid when going keto.

GOOD FATS ON KETO

The fats that get the green light when it comes to the keto diet—and good health in general—can be broken down into four categories: saturated fats, monounsaturated fats (MUFAs), polyunsaturated fats (PUFAs), and naturally-occurring trans fats. The truth is that all fats contain a mixture of these types, but the one that’s dominant is how we categorize them.

Now, we’ll break down each fat type when eating a ketogenic diet more thoroughly so you can recognize them in your own food choices.

Healthy Keto Saturated Fats

For years and years, saturated fats were seen as harmful for heart health and we were recommended to reduce them as much as possible.

However, recent studies have debunked this, showing no significant link between saturated fats, which humans have been eating for thousands of years, and the risk of heart disease. In fact, there are many benefits of including healthy saturated fats in the diet.

Plus, one type of saturated fat includes medium-chain triglycerides (MCTs), which are mostly found in coconut oil (and in small amounts in butter and palm oil) and can be digested by the body very easily. When eaten, they’re passed directly to the liver to be used immediately for energy. MCTs are great for fat loss and athletic performance.

Health benefits of saturated fats on keto can include:

  • Improved HDL and LDL cholesterol levels
  • Maintenance of bone density
  • Boosting of immune system health
  • Support in creation of important hormones like cortisol and testosterone
  • Raising of HDL (good) cholesterol in the blood to prevent buildup of LDL in the arteries
  • Improved HDL to LDL ratio

Recommended types of saturated fats while eating keto:

  • Butter
  • Red meat
  • Cream
  • Lard
  • Coconut oil
  • Eggs
  • Palm oil
  • Cocoa butter

Healthy Keto Monounsaturated Fats

Unlike saturated fats, monounsaturated fatty acids (MUFAs) have been accepted as healthy for many years. Many studies have linked them to health benefits related to good cholesterol and better insulin resistance.

Health benefits of MUFAs on ketosis can include:

  • Increased HDL cholesterol
  • Lowered blood pressure
  • Lowered risk for heart disease
  • Reduced belly fat
  • Reduced insulin resistance

Recommended types of MUFAs for a ketogenic diet:

  • Extra virgin olive oil
  • Avocados and avocado oil
  • Macadamia nut oil
  • Goose fat
  • Lard and bacon fat

Healthy Keto Polyunsaturated Fats

The important thing to remember about eating polyunsaturated fatty acids (PUFAs) on a ketogenic diet is that the type really matters. When heated, polyunsaturated fats can form free radicals, which are harmful compounds that increase inflammation along with the risk of cancer and heart disease in the body. Therefore, many PUFAs should be consumed cold and not be used for cooking.

You can find PUFAs in the forms of very processed oils as well as very healthy sources. The right types can provide a lot of great benefits as part of a keto diet, as they include both omega 3s and omega 6s, which are essential nutrients.

However, the amount is important here. Ideally, our ratio of omega 3 to omega 6 should be around 1:1. Most Western diets eat a ratio of around 1:30, so focus on your intake of PUFAs high in omega 3s.

Health benefits of PUFAs:

A healthy balance of omega 3 and omega 6 has been associated with reduced risk of:

  • Heart disease
  • Stroke
  • Autoimmune disorders and other inflammatory diseases

Intake of PUFAs may even help improve symptoms of depression and help those with ADHD, which are more benefits associated with a ketogenic diet.

Recommended types of PUFAs:

  • Extra virgin olive oil
  • Flaxseeds and flaxseed oil
  • Walnuts
  • Fatty fish and fish oil
  • Sesame oil
  • Chia seeds
  • Nut oils
  • Avocado oil

Natural Trans Fats

You might be confused to see trans fats listed under the “good” fats category. While most trans fats are very unhealthy and harmful, there’s a type of trans fat, known as vaccenic acid, found naturally in some foods like grass-fed meats and dairy fats.

Health benefits of vaccenic acid can include:

  • Reduced risk of heart disease
  • Reduced risk of diabetes and obesity
  • Possible protection against cancer risk

Recommended types of natural trans fats:

  • Grass-fed animal products
  • Dairy fats like butter and yogurt

If you’re confused on where to find this, check out this article on how to purchase the highest quality dairy. We’ll talk more below about the most common forms of trans fats, which are harmful and you want to stay far away from.

BAD FATS ON KETO

One of the great aspects of the keto diet is the ability to eat plenty of filling, satisfying dietary fats like those mentioned above. However, we must also cover the types of fats you want to reduce or completely eliminate from your diet so as not to damage your health. It is popular on a ketogenic diet to just test and confirm you’re in ketosis, but the quality of the food still matters.

Unhealthy Processed Trans Fats and Polyunsaturated Fats

Processed trans fats are the types most people are familiar with—and they can be very damaging to your health.

Artificial trans fats are formed during food production through the processing of polyunsaturated fats. This is why it’s important to only choose PUFAs that are unprocessed and not overheated or altered. Not only does processing PUFAs create harmful free radicals, but trans fats are often created from oils that contain genetically modified seeds.

Risks of consuming trans fats include:

  • Increased risk of heart disease
  • Increased risk of cancer
  • Reduced HDL cholesterol and increased LDL cholesterol
  • Pro-inflammatory
  • Bad for the health of your gut

Examples of trans fats to avoid include:

  • Hydrogenated and partially hydrogenated oils found in processed products like cookies, crackers, margarine, and fast food
  • Processed vegetable oils like cottonseed, sunflower, safflower, soybean, and canola oils

Main takeaway for fats on a ketogenic diet

Don’t fear saturated fats, choose fats that are as unprocessed as possible, and avoid fats and oils found in processed, packaged foods that were made in a factory.

After all, the purpose of the ketogenic diet is to improve your health—and that includes not only maintaining the proper fat, protein, and carb ratio but also choosing food sources that are health-promoting as well.

Sources:
https://www.ncbi.nlm.nih.gov/pubmed/20071648
http://www.ncbi.nlm.nih.gov/pubmed/12514271

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Responses (55)

  1. Hooray on goose fat being ok. I suspect that mammal fat should be avoided but not fatty birds!

  2. I really enjoyed the your article. I had the question of “are all fats ok on the keto diet?” Im glad that you got that cleared up. I was beginning to wonder if the keto diet had any limits lol.

  3. it says Processed vegetable oils are bad like sunflower but above we can see sunflower is an healthy Monounsaturated Fat sorry im confused and really want to know the difference or how to spot the difference while buying cooking oil.

  4. My concern on Keto….saturated fat raises bad cholesterol levels; especially if you already have high cholesterol and are takin a statin. How can we eat bacon fat, cream and full fat dairy????

  5. Cook with gras fed Kerrygold Salted or Unsalted butter. I use a table spoon usually. I’ll also use a table spoon of Coconut oil to cook with, but it lacks flavor so the grass fed butter gets more servings!

  6. ”When heated, polyunsaturated fats can form free radicals, which are harmful compounds that increase inflammation along with the risk of cancer and heart disease in the body. Therefore, many PUFAs should be consumed cold and not be used for cooking.”

    Fish is listed in the good fats….so question, does the ”heated” part also apply to fish? Or only to the oils listed…I will stop cooking with Olive Oil immediately. I will start saving and chilling bacon fat now though. But I can’t eat raw fish LOL

  7. Hi, I’ve just started a ketogenic diet & would like to know what oil/s are best used for deep frying? TIA

  8. You mention omega 3 to omega 6 levels are typically 30:1, but I believe you meant 1:30? Otherwise we would need to reduce omega 3 to get down to 1:1 as suggested. I doubt that’s correct.

  9. Leigh – I have been eating keto for 2.5 years, my cholesterol has gone down bacon and all – with no statins

  10. You are very misinformed (by old bad science most likely… or doctors). If the body doesn’t get large amounts of cholesterol, it freaks out and makes its OWN cholesterol and doesn’t know when to stop. But if you take in a lot of cholesterol from your FOOD, you’re good to go. The body doesn’t start up a cholesterol factory that goes haywire.

  11. It doesn’t! Old beliefs 😉 However, the quality of these animal products is still SO important! Grass-fed, pasture-raised, free-range, organic animal products is a must if you will be purchasing these items 🙂

  12. Is pork fat really ok? I used to eat pork but stayed away from the fat. Now I’ve switched to keto and would eat the fat. I eat bacon on a regular basis. I’m afraid I might clog my arteries and damage my heart.

  13. I make a spread out of softened Kerry Butter ” salted ” and softened Coconut Oil ” virgin ” I just whip 1 cup Kerry and 1 cup Coconut Oil with my electric mixer till its fluffy then if its warm weather I keep it in the fridge but if its a cool season I leave it out on the counter because Coconut Oil has a very long shelf life tastes great .

  14. Hi Gretchen, coconout oil is my go-to or you could use ghee, tallow, or duck fat which are great options as well.

  15. Are you saying that heating Avacado oil creates feee radicals? I thought it was ok to use avacado oil in cooking.

  16. Hey Collin, avocado oil is a MUFA (mono-unsaturated fatty acid) which are less stable than SFA (saturated fatty acids) like coconut oil and butter when heated. Avocado oil is best used for lighter cooking and using SFA are best for high heat cooking. If it is a refined avocado oil, it will have a higher smoke point than unrefined and could probably be used for a bit higher cooking. But to be safe, stick with the saturated fats for high heat cooking because they are more stable and less likely to create free radicals.

  17. I have a food intolerance to all fruit, including coconut, avocados berries etc. I Use mostly walnut oil and butter or ghee. For cooking oil, like sautering veggies, what would be best to use. My daughter can not have dairy products so when she is with us butter is out. Is walnut ok for low temp cooking?

  18. Hey Mary, unrefined walnut oil should be okay for low temp cooking. I’d stick with ghee as much as you can or use things like beef tallow or leftover bacon fat!

  19. Atkins was low carb High Fat High Protein. So just saying it was high protein is misleading. Most people could still enter Keto on the traditional atkins diet.

  20. Kale, Brussels sprouts, spinach leaves, few carrots, tomatoes (for potassium). Make sure you average them into your carb count. The net carb on these are not super high

  21. Thankyou. That sounds like the perfect suggestion. There is no mention of milk. Should we drink full cream milk or alternative?

  22. I would like to point out that the WHO now classifies processed meat, such as bacon, sausage, etc. as a type one carcinogen. If the Keto diet endorses the elimination of processed food that needs to include processed meats as well.

  23. I also worry about over heating oils while cooking. I purchased a Sous-vide (water bath oven) that allows me to precisely control the temperature while cooking. It’s a bullet proof method of retaining as much of the nutrients from meats by cooking them as gently as possible. I add the olive or other delicate oils to the meat when it’s on the plate. The startup cost to cooking this way can be significant though, but I figured that my health was worth it. It also added a valuable time saving tool to my kitchen arsenal.

  24. Great post doing the Bulletproof Coffee and the diet that goes along with it getting good results.

  25. Hello. I came across this post when trying to research nuts that are suitable for keto. Would you recommend roasted and salted or raw brazil/pecans? I noticed that most are roasted in sunflower oil which makes me think it’s not a good idea. I just need an emergency salty snack once in a while! Any suggestions please?

  26. I still need help calculating the macronutrients. My husband is 5 ft 3″. He weighs 242 and is 68. I am female and 5′ 227lb and 65. He plays volleyball in pool 3 days a week. I am handicapped but work part time

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