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
- 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.