Fats: the truth!

In summary, saturated fats are good, trans fats are bad. Monounsaturated and polyunsaturated fats are for cold use only and the latter must be consumed in moderation, to avoid an excess of omega-6. Want to know more? Read on!


Saturated fatty acids (SFAs) are lauric, myristic, palmitic and stearic acids, and contain only single bonds between the individual carbon atoms of the fatty acid chain. As such, they are fully ‘saturated’ with hydrogen atoms, making them extremely heat, light and oxygen stable. This is a good thing!  So it is this exact reason why SFAs should be used for cooking wherever possible. It is our body’s full time job to battle cellular damage, so please don’t add to the equation by consuming damaged oils (i.e. polyunsaturated or monounsaturated oils or fats at high temperatures – more on this to come).

Unlike what you may have been told, saturated fats DO NOT cause heart disease!
Since the 1950’s, we have been told that saturated fats increase our cholesterol, which in turn leads to cardiovascular disease – both of which could not be further from the truth. In my opinion, this is the biggest nutrition myth of the century, now with research to support it. In 2010, twenty-one past studies were included in a meta-analysis of 347,747 individuals. The results of this study clearly state there is “no significant evidence for concluding that dietary saturated fat is associated with an increased risk of heart disease”. You can access the research here. Amen.

How did this happen?
It’s a really long story involving the words “conspiracy”, “spin doctors”, “brainwashed” and “political decisions”, but for a simplified version of how it all started, my article “Sugar is the Devil” and this short clip, “The saturated fat myth debunked in two minutes and thirty five seconds” will help. For the full details, I highly recommend “Good Calories, Bad Calories” by Gary Taubes.

 The facts

  1. It is important to note that much of the initial research was conducted on rabbits, whose natural diet does not include cholesterol-containing food. Our cholesterol metabolism is essential for human life and of course, vastly different to rabbits.
  2. Prior to the industrial revolution, saturated fats were the most prominent sources of fat in the human diet and sustained our ancestors for centuries. Our ancestors may have died young, but it certainly wasn’t due to the consumption of margarine, seed oils, fried foods or refined sugar! I’m pretty sure lack of shelter, the absence of modern medicine and hunting for your dinner would kill you off early too!
  3. Dietary cholesterol only raises blood levels by 1-2%, so its effect is only ever going to be mild. The even better news is that saturated fat actually exerts a positive influence on our high density lipoprotein (HDL), otherwise known as our “good” cholesterol. Another good thing!  The role of HDL is to transport cholesterol away from our  arteries and towards the liver, where it may be either excreted or reused.

I repeat, cholesterol is essential to human life. To quote Kris Gunnars, the head of Authority Nutrition, “without cholesterol, we would die… and our bodies have developed elaborate mechanisms to manufacture it, to make sure we always have enough”.

In case you’ve been living under a rock, trans fats, refined polyunsaturated fats and refined sugar (think high fructose corn syrup, HFCS) are the culprits. Inflammation is the cause of heart disease. Stop eating processed food products and watch your health status (and weight) improve!

SATURATED FATS continued..

The benefits
I could go on for hours about the benefits of SFAs, but in short they provide the building blocks for our cell membranes and hormones, and act as a carrier for our important fat-soluble vitamins A, D, E and K. Pretty essential huh? Saturated fat is a concentrated source of energy and is therefore blood sugar and insulin steadying. These are the keys to energy, satiety and weight control. Full stop.

The sources
SFAs are found in coconut oil^, butter, ghee, cocoa butter, beef fat, lamb fat, shellfish and in our full fat dairy foods – milk, cream and cheese*. Eat these. Throw your low fat products in the bin please!

^Coconut oil is definitely my fave! Read why here.

*If you choose to drink dairy, choose full fat, unpasteurized and organic wherever possible. To turn skim milk white, it is often fortified with powdered skim, which is liquid sprayed under heat and high pressure, a process that oxidizes the cholesterol. In animal studies, oxidized cholesterol triggers a host of biological changes, leading to plaque formation in the arteries and heart disease. Need I say more.


Monounsaturated fats (MUFAs) include palmitoleic acid, cis-vaccenic acid and oleic acid, and contain only one reactive double bond in their molecular structure, making them far less prone to oxidation than polyunsaturated fats. They are still not fully ‘saturated’ however, so MUFAs are for cold use only.

The benefits
Like SFAs, MUFAs are a preferential source of fuel for the body. As we have discussed, fats are a concentrated source of energy and therefore blood sugar and insulin steadying. When compared to carbohydrates, they provide a steadier supply of energy and should therefore be prioritized to control fluctuations in mood, hunger and weight. Including the right types of fat in your diets (i.e. SFAs and cold MUFAs) is the key to energy, satiety and weight control.

The sources
MFAs are found in beef, lard, olives and olive oil, macadamia nuts and macadamia nut oil and avocado and avocado oils. Eat these, but exercise caution. Nuts, seeds and avocados in particular, also contain omega-6 polyunsaturated fats, so please always be mindful of your intake. More on this to follow.


Polyunsaturated fats (PUFAs) include omega-3 and omega-6 fatty acids, and contain multiple double bonds in their molecular structure. The highly ‘unsaturated’ nature makes them incredibly unstable in the presence of heat, light or oxygen. This is not a good thing!  Please do not heat PUFAs, as their unstable nature means they turn rancid and toxic at high temperatures. Remember, it is our body’s job to fight oxidative damage, so denatured polyunsaturated oils must be avoided.

  • Omega-3 PUFAs

These are commonly found in marine and plant oils, grass-fed beef and eggs. Eat these! Eat two pieces of oily fish per week and do not supplement with cheap fish oil. Many of the benefits you may have heard on fish oil supplementation are not approved health claims, nor supported by adequate clinical trials. In some brands, anti-inflammatory effects have now been found to occur via immune suppression (i.e. weakness of the immune system), which is definitely not a good thing! Eat an anti-inflammatory diet (i.e like our ancestors did) and the health benefits will be clear. Supplementation should always be secondary to nutrition.

  • Omega-6 PUFAs

These are found in margarine, canola oil, sunflower oil, grapeseed oil, peanut oil, sesame oil, safflower oil and corn oil. Avoid these! Seed, vegetable and any hydrogenated oils are highly inflammatory and remember, inflammation is the cause of heart disease. Please throw your vegetable and seed oils in the bin! For more information, read Ray Peat’s take on unsaturated oils. I also highly recommended Toxic Oil by David Gillespie.

As mentioned, omega-6 PUFAs are also found in less concentrated sources in nuts, seeds and avocados. Eat these in moderation.

Omega-6 v Omega-3: Getting the Balance Right
Our ancestors survived on an omega 6:omega-3 ratio of one, whereas some Western diets can be as high as 25:1. The ideal intake is thought to be independent to disease, but to reduce the risk of disease in the first place, the lowest ratio of omega-6:omega-3 fatty acids is the most desirable.

In saying this, I’m certainly not advising you to eat by numbers. After all, biology does not equal math. In case you need a gentle reminder, please watch my all-time favourite clip, “Slim is Simple”.

So what fats should I eat?!

Lots of coconut oil, butter, ghee, cocoa butter, beef fat, lamb fat and shellfish.

Oily fish: salmon, trout, mackerel, sardines and anchovies.

A little unpasteurized full fat dairy*.

Olive oil as a salad dressing or cold poured.

Macadamia nuts and avocados in moderation.

Some nut flours, nut milks and seeds. (Which I’ll admit, even I find challenging).


As I always say, pick your battles. Trans fats, refined polyunsaturated fats and refined sugar are the culprits. Avoid these. Keep it simple: eat real food.


Harris WS et al. (2009). Omega-6 fatty acids and risk for cardiovascular disease: a science advisory from the AHA Nutrition Subcommittee of the Council on Nutrition, Physical Activity and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation, 119(6), 902-7.

Kraus R et al. (2006). Saturated fat in the diet does not raise serum cholesterol. American Journal Clinical Nutrition, 84(6), 1550.

Patty W et al. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. American Journal of Clinical Nutrition, 91(3), 535-546.

Peat R. (2007). Unsaturated vegetable oils: toxic. Available:

Simopoulos AP. (2000). Human Requirement for N-3 polyunsaturated fatty acids. Poultry Science, 79(7), 961-70.

Simopoulos AP. (2002). The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomedicine & Pharmacotherapy, 56(8), 365-79.


* I’m not telling you that you have to eat dairy – this is obviously optional, and your decision entirely.


  1. Meadhbh Bolger

    Hi! Thanks for a great article! Buuuuuut……I am now worried that I eat too much omega 6!….I have approximately a quarter to half an avocado everyday plus approximately 50g of nuts everyday! Is this too much? Or how do I increase my intake of omega 3 to know it matching? Thanks!

  2. Ros

    Thanks for a brilliant article! I had been educating myself about healthy and unhealthy fats and you have explained it so clearly and made it simple to understand.

  3. Steph

    I’m so glad Ros! Thanks for your support.

  4. Steph

    Hi Meadnbh, I feel the same as you but there is actually much more to it. I now am researching into a good quality fish oil to increase omega-3 without the immunosuppressant link. Stay tuned for a blog post!

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  10. Chris

    I have heard that we should use avocado oil when cooking at hight heat over olive oil. Is this true? Or is there a better alternative? Ray peat didn’t directly mention avocado oil.

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