Good Fats vs. Bad Fats on the Ketogenic Diet
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Good Fats vs. Bad Fats on the Ketogenic Diet

There's more to a ketogenic diet than just eating fat. Learn what type of fats are the best for keto and which ones to avoid.

Good Fats vs. Bad Fats on the Keto Diet

On a high-fat keto diet, roughly 70% of your calories will come from fats. If you’re just starting a low-carb, healthy lifestyle, you may be wondering which fats are best for your health, and which are best avoided. To help clear things up, this guide will outline the differences between good fats vs. bad fats.

You’ll learn about the different kinds of fats and keto-friendly food sources for each. Plus, you’ll learn about where the “fat is bad” myth originally came from, and how it has since been debunked by science.

Good Fats on Keto

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 healthy fats contain a mixture of these four types of fat. However, the fat that is most dominant (or can be found in the highest traces) within a given food source determines how that food is categorized.

Healthy Keto Saturated Fats

For years and years, saturated fats were seen as harmful for heart health. This led to the low-fat and fat-free craze around the 1970s, which is still preached by the American Heart Association. However, even this organization is slowly coming around to the idea that fat intake is part of a heart-healthy diet (although they continue to demonize saturated fats).

Recent studies have debunked the AHA’s claim, showing no significant link between saturated fats — which humans have been eating for thousands of years — and the risk of heart disease[*].

In fact, in the case of good fats vs. bad fats, there are many benefits of including healthy saturated fats in your diet, including balanced hormones, improved cognition, and better absorption of nutrients[*][*][*].

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. These fats can be digested by the body very easily and, when eaten, they’re passed directly to the liver to be used immediately for energy.

MCT oil comes with some incredible health benefits, including improved gut health, appetite suppression (thereby potential weight loss), enhanced cognition, a boosted immune system, reduced risk of heart disease, and improved athletic performance[*][*][*].

Good sources of saturated fat to include in your keto meal plan are red meat, butter, ghee, heavy cream, lard, coconut oil, eggs, palm oil (try to purchase a sustainable brand), and cocoa butter. When purchasing animal fats such as meat, eggs, and dairy products, always choose the highest quality you can reasonably afford, including grass-fed meat and dairy, and pasture-raised eggs.

Health benefits of saturated fats on keto can include:

  • Improved HDL and LDL cholesterol levels, including raising HDL (good cholesterol) to prevent the buildup of LDL (bad cholesterol) in the arteries[*]
  • Maintenance of bone density[*]
  • Boosting of immune system health[*]
  • Support in creation of important hormones like cortisol and testosterone[*]

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[*].

MUFAs can be found in many foods touted as healthy, and are a popular cornerstone of the Mediterranean diet. MUFA sources include extra virgin olive oil, avocados and avocado oil, macadamia nut oil, goose fat, cashews, pecans, lard, and bacon fat[*].

Health benefits of MUFAs on ketosis can include:

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

Healthy Keto Polyunsaturated Fats

Here’s the important thing to remember about eating polyunsaturated fatty acids (PUFAs) on a ketogenic diet: How you use them matters. When heated, polyunsaturated fats can form free radicals, which are harmful compounds that increase inflammation along with the risk of cancer and cardiovascular disease in the body[*]. Therefore, many PUFAs should be consumed cold (such as in salad dressings) and not be used for cooking, and always be stored at cool or room temperatures.

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-3 and omega-6 fatty acids, which are essential nutrients. However, the amount of each is important.

Ideally, your ratio of omega-6 and omega-3 fatty acids 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.

Healthy forms of PUFAs including extra virgin olive oil, flaxseeds and flax oil, walnuts, fatty fish (like salmon) and fish oil, sardines, mackerel, sesame oil, chia seeds, nuts and nut butter, and avocado oil. Certain sources, like corn oil and canola oil, should be avoided.

Health benefits of PUFAs can include:

  • Decreased risk of heart disease and stroke[*]
  • Decreased risk of autoimmune disorders and other inflammatory diseases[*]
  • Improved mental health, reducing symptoms caused by depression or ADHD[*]

Natural Trans Fats

When it comes to good fats vs. bad 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. This type of fat can be found in animal products and dairy products like grass-fed butter and yogurt.

Health benefits of vaccenic acid can include[*]:

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

Bad Fats on Keto

One of the great aspects of the keto diet is the ability to eat plenty of filling, satisfying dietary fats. That said, it’s important to learn about the types of fats you may want to reduce (or completely eliminate) from your diet, as they can cause adverse health effects.

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, overheated, or otherwise altered. Not only does processing PUFAs create harmful free radicals, but trans fats are often created from oils that contain genetically modified seeds.

Examples of trans fats to avoid include hydrogenated and partially hydrogenated oils found in processed products like cookies, crackers, margarine, french fries, and fast food. You will also find them in processed vegetable oils like cottonseed oil, sunflower oil, peanut oil, safflower oil, soybean oil, and canola oil.

Risks of consuming trans fats include[*]:

  • Increased risk of heart disease
  • Weight gain and increased body fat
  • Increased risk of cancer
  • Reduced HDL cholesterol and increased LDL, or bad cholesterol
  • Pro-inflammatory
  • Bad for the health of your gut

Good Fats vs. Bad Fats: Now You Know

Including quality sources of fats is a part of any healthy eating plan — not just a high-fat, low-carb diet like keto. By including healthy choices like avocados, extra virgin olive oil, grass-fed meat, and full-fat dairy products in your diet, you may experience a number of health benefits.

While grocery shopping and choosing between good fats vs. bad fats, don’t fear saturated fats. You should, however, be wary of trans fats and processed seed and vegetable oils.

Remember, the purpose of the ketogenic diet is to improve your health. This means maintaining the proper balance of macronutrients (fat, protein, and carbohydrates), and choosing healthy choices of each. For more ideas on healthy fat choices, this guide on healthy fat foods to learn which foods to avoid, and which to enjoy.

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60 thoughts on “Good Fats vs. Bad Fats on the Ketogenic Diet

      1. 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.

  1. 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.

    1. 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.

      1. 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!

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

  2. 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????

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

    2. 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.

    3. 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 🙂

    4. 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.

  3. ”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

  4. 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.

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

  5. 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.

  6. 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 .

    1. 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.

  7. 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?

    1. 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!

    1. 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

  8. 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.

  9. 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?

  10. 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

  11. If fat is being used as fuel and not stored why should it make a difference if you eat good or bad fats on a keto diet

    1. Hi Steve, the purpose of the ketogenic diet is to improve your health—and that includes choosing food sources that are health-promoting as well. 🙂

  12. @John so long as it’s not breaded, Dry rubs (Parmesan garlic) and buffalo style wings are okay. Dip in bleucheese or ranch. Stay away from sugary sauces, mango, bbq, honey mustard. Some are okay if made with keto in mind, but i don’t think restaurants use low sugar bbq sauces. But should be okay if you make and use your own.

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