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Good Fats vs. Bad Fats on the Ketogenic Diet

The ketogenic diet is a high-fat diet that’s great for weight loss, mental clarity, and more. 

On a keto diet, you get about 70% of your calories from fats, and for your long-term good health, you want to make sure you’re eating healthy fats. 

Not all fats are created equal — some are great for you, while others contribute to heart disease and increased  overall disease risk. It’s important to know which fats are good for you, especially if you’re going to follow a high-fat, low-carb diet. 

To help clear things up, this guide will outline the differences between good fats vs. bad fats.

Good Fats on Keto

good fats vs. bad fats

The four main types of fats that exist in diet are:

  • Saturated fats 
  • Monounsaturated fats (MUFAs) 
  • Polyunsaturated fats (PUFAs)
  • T rans fats

Within each of these categories, there’s a fair amount of variety — for example, omega-3s and omega-6s are each a type of polyunsaturated fat, but while omega-3s are great for you, excess omega-6s are unhealthy fats. 

Similarly, naturally occurring trans fats are fine, but artificial trans fats are a massive contributor to heart disease, and are illegal in many countries. 

Here’s a look at the healthy fats in each category. 

Healthy Keto Saturated Fats

For years, dietary guidelines suggested that you avoid saturated fat. The suggestion came from a flawed study back in the mid-20th century that found a modest correlation between heart disease and saturated fat intake. 

At the time, obesity and heart disease were increasing dramatically in the United States, and the government was desperate for a reason why. While the saturated fat research was far from conclusive, it was the best thing they had — so they took the idea that saturated fat is bad and ran with it, making low-fat dietary guidelines their new standard for health. 

This led to the low-fat and fat-free craze around the 1970s — an idea still preached by the American Heart Association

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However, more robust research is now coming out on the topic, and ideas about fat and diet are changing. It’s clearer and clearer that to the idea that fat intake is part of a heart-healthy diet

Recent studies show no significant link between saturated fats 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 hormone balance, brain health, and liver function [*][*][*].

Most animal fats are saturated, including beef, pork, lamb, and to a lesser degree, chicken. 

There are also plant sources of saturated fat. Tropical oils like coconut oil and palm oil are rich in a special class of saturated fats called medium-chain triglycerides (MCTs). Your body burns MCTs very quickly, giving you immediate energy without spiking your blood sugar the way refined carbs do. 

MCT oil comes with powerful health benefits, including better gut health, appetite suppression (which leads to potential weight loss), sharper mental clarity, a stronger immune system, lower risk of heart disease, and better athletic performance[*][*][*].

MCT oil is a great fat to eat on a keto diet. Other good sources of saturated fat include:

  • Red meat
  • Butter and ghee (preferably grass-fed)
  • Heavy cream, cheese, and other full-fat dairy products
  • Lard
  • Eggs (preferably pasture-raised; look for deep orange-yellow yolks, which are the sign of a healthy animal and greater nutrient density)
  • Coconut oil
  • Palm oil (look for a sustainable, rainforest-certified brand; unsustainable palm oil farming destroys rainforests)
  • Cocoa butter and dark chocolate

Saturated fats are an essential part of a balanced keto diet. In the context of a keto diet, health benefits of saturated fats include:

  • Improved HDL and LDL cholesterol levels, including raising HDL (good cholesterol) to prevent the buildup of LDL (bad cholesterol) in the arteries[*]
  • Strong bone density[*]
  • Immune health[*]
  • Healthy sex hormone production (testosterone, human growth hormone, estrogen, progesterone, etc.)[*]

Healthy Keto Monounsaturated Fats

Unlike saturated fats, monounsaturated fatty acids (MUFAs) have been accepted as healthy for many years. Many studies link MUFAs to health benefits like good cholesterol and insulin sensitivity[*].

MUFAs are a staple of the Mediterranean Diet, and you’ll find them in a lot of healthy foods. Good sources of monounsaturated fats include[*]:

  • Olive oil
  • Avocados
  • Avocado oil
  • Cashews, pecans, macadamia nuts, almonds, and other nuts
  • Bacon fat

Health benefits of monounsaturated fats include:

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

Healthy Keto Polyunsaturated Fats

Polyunsaturated fatty acids (PUFAs) can either be great for you or actively bad for you, depending on how you use them. 

PUFAs are quite delicate — if you heat them too much, they break down and form compounds called free radicals. Free radicals contribute to cardiovascular disease, inflammation, and other health problems[*]. 

As a rule of thumb, you’re best off eating PUFAs in uncooked form (e.g. in salad dressings) and storing them in a dark place at cool room temperature. 

The two most important types of PUFAs are omega-3 and omega-6 fatty acids. Your body needs both of them, but the ratio of the two 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 30:1 in favor of omega-6s, and the skewed ratio can cause inflammation and contribute to heart disease, cardiovascular disease, and other chronic diseases[*].  

Ideally, most of the PUFAs you eat will be omega-3s, or at least will have a balance of omega-3s and omega-6s. 

Healthy sources of PUFAs include:

  • Extra virgin olive oil
  • Wild-caught fatty fish (salmon, sardines, mackerel)
  • Fish oil
  • Sesame oil
  • Chia seeds
  • Raw nuts and nut butter
  • Avocado 

Avoid refined vegetable oils like corn oil and canola oil — they’re billed as heart-healthy, but are mostly omega-6s. 

Health benefits of high-quality PUFAs include:

  • Decreased risk of heart disease and stroke[*]
  • Decreased risk of autoimmune disorders and other inflammatory diseases[*]
  • Improved mental health, including relief from depression and ADHD[*]

Natural Trans Fats

You might be confused to see trans fats listed under the “good” fats category. 

Most trans fats come from vegetable oils that manufacturers hydrogenate in a lab, making them solid instead of liquid.

These trans fats don’t occur in nature and your body doesn’t know how to process them, and they contribute massively to heart disease risk[*] — so much so that vegetable-based trans fats are illegal in many countries. 

However, there’s a healthy type of trans fat, known as vaccenic acid, found naturally in animal and dairy products, like grass-fed meats, butter, and cheese. 

Vaccenic acid is perfectly good for you. 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

good fats vs. bad fats

One of the great aspects of the keto diet is that you can fill up on plenty of dietary fats, making it easier to lose weight and stay satisfied with your diet long-term. 

That said, it’s important that you choose healthy fats and avoid unhealthy ones. Here’s a list of fats you may want to reduce while eating any diet, and a keto diet in particular. 

Omega-6 Polyunsaturated Fats

Omega-6 fatty acids are the unhealthy fats you read about earlier — most Americans get far too many of them. Excess omega-6 fats can contribute to inflammation and heart disease[*].  

The most common source of omega-6 fats is vegetable oil. Use the following vegetable oils sparingly, or avoid them entirely:

Artificial Trans Fats 

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

Artificial trans fats are largely illegal now, but manufacturers still find ways to hide them in products by exploiting loopholes in nutrition labeling. 

You may still find trans fats in the following ingredients:

  • Hydrogenated and partially hydrogenated oils
  • Mass-produced cookies
  • Crackers
  • Margarine
  • French fries
  • Fast food

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
  • Bodywide inflammation
  • Imbalance in gut bacteria

Good Fats vs. Bad Fats: Now You Know

good fats vs. bad fats

Good fats are part of any healthy eating plan, and they’re especially important on a keto diet. You’ll see and feel the difference if you focus on eating healthy fats like avocados, extra virgin olive oil, grass-fed meat, and full-fat dairy products, and if you avoid vegetable oils and trans fats.

Want to prioritize high-quality fats? Our recipe archives make it easy for you to find plenty of delicious recipes that use only healthy fats.


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