Eat Primal 5 Week Challenge – Week 4 – Know Your Fats

Last week, we looked at how the role of carbohydrates in your diet should vary, depending on your goals and lifestyle.

This week, we’re looking at fats – an equally, if not more contensious topic!

The Good, the Bad and the Ugly?

For most of the latter part of the 20th century, the universal message was pretty much “Fat is bad”:

Fat makes you fat, and causes heart disease and atherosclerosis, remove it from your diet as much as possible.

Since the 90s, however, the message began to become a little more nuanced, as people recognised that different fats have different chemical structures, different roles in the body, and are processed in different ways.

Nowadays, pretty much all scientists and nutritionists agree that there are good fats, bad fats, and ugly fats.

But of course, no one can agree exactly which is which.

Hydrogenation makes you Ugly

When it comes to fats, there is one thing that pretty much everyone agrees on.

  • Industrial Transfats are seriously bad news

Consensus is rare in the world of nutrition, because the science is notoriously hard to conduct.

There are so many variables and confounders, signals can get lost in the mix, and false alarms and correlations pop up all the time.

For one particular ingredient to flag up such strong warning signs that it’s a risk to your health, it’s got to be wreaking some pretty serious damage.

Partially Hydrogenated Vegetable Oils (PHOs) have managed to do just this.

Transcendental Fat Josch13 / Pixabay

Industrially manufactured transfats are made by bombarding polyunsaturated fats with hydrogen ions, to alter their molecular structure so that they are solid at room temperature.

This means that they can be used in place of saturated fats in the making of cakes, biscuits, pastries, ready meals and a whole host of other processed products. Pretty much everything you find in a packet on the supermarket shelves.

They were initially invented as a “healthier alternative” to saturated fats. Whether this fear of saturated fats was warranted or not we’ll address shortly, however, it soon became apparent that transfats were not the healthy alternative they’d been intended to be.

Turns out that bombarding fat molecules with hydrogen ions to alter their molecular structure has unforeseen consequences. The process creates free radicals. These are the same bad boys in cigarette smoke, which when in the body, careen around causing oxidative damage wherever they go.

Consumption of hydrogenated vegetable oils have been shown to increase your risk of heart disease, atherosclerosis, diabetes and cancer.

The evidence is so strong, that Denmark, Iceland, Sweden, Austria, Switzerland, New York, and Brazil have all outlawed the use of industrial transfats in food, and recently the US has removed its “GRAS” status (Generally Recommended as Safe), which means its use will have to be gradually phased out.

Unfortunately, the UK and much of Europe have done pretty much nothing.

I said before, “pretty much everyone” agrees that PHOs are ugly. The exception of course would be the food industry. Another, unintended(?) consequence of the invention of industrial transfats was that they were considerably cheaper than traditional animal based fats.

Food manufacturers are reluctant to remove them from their products as it will hurt their profits.

The UK government are reluctant to ban their use, or even to make their labelling on food packets mandatory, for this same reason, despite doing so could prevent an estimated 11000 heart attacks and 7000 deaths per year.1

Just a reminder of whose interests they act for… but I digress!

Needless to say, regardless of your goals, avoid these fats at all costs.

If you are living in the UK, Spain or any other country which still hasn’t taken action, you’re going to have to take extra special care to avoid PHOs.

Though food labels don’t have to have an explicit warning, they do have to list all the ingredients on their. Check the ingredients list for “shortening,” “partially hydrogenated vegetable oil” or “hydrogenated vegetable oil,”.

If a food has any of these, put it back on the shelf. To save time, better just to avoid foods which have food labels. For more info, check this handy guide to navigating the supermarket shelves for healthy food.

Generally Accepted as Good

While everyone who’s not making a profit out of it agrees that industrial transfats are bad, agreeing on what, if any, fats are good has proven more tricky.

Generally speaking, however, the majority of experts agree that monounsaturated and polyunsaturated oils are “Good Fats”, also commonly termed “Heart Healthy Fats”.

When we talk about monounsaturated and polyunsaturated fats (MUFAs and PUFAs), we are usually referring to “vegetable oils” – that is oils extracted from plant sources – usually from seeds and nuts, though also of course olives, soy beans, and various other plants (though rarely actually vegetables!).

MUFAs and PUFAs are also found in animal products however, such as fish, eggs, dairy and meat.

Bad Ass MUFAs

Everyone loves MUFAs! These are fatty acid chains with one hydrogen missing, creating a single double bond between 2 carbon atoms. MUFAs are liquid at room temperature, and solidify in the fridge.

The most common sources of MUFAs in the diet are Olive Oil, Avocados and Nuts.

Poster child of the mediterranean diet, olive oil has been credited with reducing risks of heart disease, high blood pressure, stroke, cancer and even depression.

Nut consumption has also been strongly associated with lower BMI, better health and longer life expectancy, and the research on avocados is pretty favourable too.

MUFAs are clearly some kind of magical panacea for all life’s ills. Let’s go whizz up a smoothy made from a litre of olive oil, a jar of nut butter and a couple of avocados!

Beware Nutritionism


It’s true that Mediterranean people who followed a traditional diet, cooking daily with olive oil, generally live longer and healthier lives than people eating a modern processed diet.

Attributing these gains to olive oil, let alone isolating the MUFA component of it, is a bit of a stretch, to say the least.

It could simply be the “cooking daily” part, it could be the reduced consumption of PHOs and sugar, and the higher consumption of fresh vegetables. It might simply be living in the Mediterranean with the more relaxed attitude to life and better weather!

The Secret Ingredient to Healthy Living? stevepb / Pixabay

Regular nut consumption has also been shown in numerous studies to be beneficial, but again, there’s really not enough evidence to definitively pin these benefits on the MUFAs – perhaps it could be the protein, or the minerals, or simply because they’re not crisps or popcorn…

Now, I don’t want to bash MUFAs – quite possibly they are healthy for us – what I do want to do is have you beware of nutritionism. That is, the belief that an isolated nutrient has special powers, and that more is always better.

Personally, I eat olive oil and unsalted nuts on a daily basis, and avocados several times per week, usually altogether in a huge salad with lots of other veggies for lunch.

For me, the true marvel of olive oil, is that it makes vegetables delicious, and therefore helps me eat more of them, be it in the form of a salad dressing, drizzled over steamed veg, or in stir-frying.

Huff and PUFA

If you haven’t heard of “The Benefits of Omega 3”, then you must surely have been living under a rock for the last 10 years.

By taking a little capsule of fish fat, you can not only avoid all modern disease, but also increase your IQ. Awesome!

Ah, if only it were true. Unfortunately, if you are drinking the fish fat cool aid, you have succumbed to the aforementioned nutritionism.

PUFAs are so-called because they are missing multiple hydrogen ions, which makes them really kinky. So kinky they won’t even totally solidify in your fridge.

A certain subset of PUFAs, omega 3s and omega 6s, are categorised as “Essential Fatty Acids” (EFAs).

This is because they are required by the body to make (among other things) eicosanoids (affecting inflammation and many other cellular functions) and endocannabinoids (affecting mood, behavior and inflammation).

The Health Benefits of the PUFA Fish?dab306 / Pixabay

Now, there is 100% consensus that these Omega 3 and 6 fats are essential to human health. Where things begin to go awry is in deciding how much of them we should consume, and from what sources.

  • More is better

If something is essential, then surely more is better?

Well not necessarily. When it comes to body chemistry, dose is important. Too much of pretty much any essential nutrient can be toxic. Factoid: If you were to eat a polar bear’s liver, you’d die from the Vitamin A poisoning!

The main proponents of this approach, are unsurprisingly those that manufacture and or sell EFA supplements…

  • It’s all about balance

Another argument, is that the modern diet has created an imbalance between Omega 3 and Omega 6 fats.

Our ancestral diet often involved eating brains (very high in Omega 3), pasture raised meat (higher in Omega 3 than industrially farmed grain fed meat), and plenty of fresh fish and seafood.

Modern diets are generally lower in all these foods, while much higher in industrially processed vegetable oils such as sunflower oil, soybean oil, rapeseed oil etc.

This change in diet, favouring Omega 6 consumption, could be a potential cause of inflammation, which in turn is thought to be an underlying cause of all the modern NCDs that currently plague society, from obesity, to heart disease, diabetes and cancer.

It’s an interesting theory, which perhaps may be true, but as yet, the evidence is far from conclusive.

As you may already have guessed, the fish oil pedlars recommend redressing this balance by increasing your Omega 3 consumption.

Even if the balance theory turns out to be true, I’d caution against that approach however, for the same reasons as above.

A more sensible approach would be to reduce your Omega 6 consumption. As the major source of Omega 6 fats in the modern diet is processed junk food, this is a strategy I can get behind. Cut out processed foods high in Omega 6 fats and you’ll also invariably reduce transfats, sugars and lots of other junk at the same time.

  • Quality, not Quantity

Polyunsaturated Fats are very delicate, and can oxidise easily. Oxidised PUFAs could potentially cause free radical damage in the same was as transfats.

Industrially produced oils tend to be extracted at high temperatures and pressures, often with the use of chemicals, leading to a high chance that the fats will become “rancid”.

It is argued that the oxidative stress caused by these rancid fats, could be a contributing factor to many NCDs.

Again, the evidence behind this theory is not as strong as that against PHOs, but regardless, I think the recommendation to go for quality, non rancid oils, is pretty sound:

Oily fish, pastured eggs, nuts and seeds are all great sources of unprocessed PUFAs, the consumption of which are strongly associated with good health and longevity.

Processed meals and junk foods are the main sources of processed PUFAs, and are strongly associated with poor health, and increased mortality risk.

Most fried foods, are now fried in PUFAs. The high temperatures used for frying in turn cause yet more oxidation and damage to the fats – this coupled with the very high calorie content helps explain the very strong link between deep fried foods and heart disease, artherosclerosis, stroke and cancer.

So what to do?

Whether or not the benefits of swapping processed and deep fried foods for more fresh wholefoods such as fish, eggs, nuts and seeds comes from changing the balance, quality and or quantity of PUFAs or not remains to be seen, but it will most definitely have benefits!

It should also be noted, that while there are undoubtedly benefits to eating oily fish, the same benefits have not been shown to be gained from Omega 3 supplements. Whether this is because the EFAs in supplements are poor quality (if there are even any in there at all), or because the sum of a fish is greater than it’s parts is unclear. Forget the capsules, have some delicious fresh fish instead!

Artery Clogging Saturated Fat?

Everyone knows that saturated fat makes you fat and clogs your arteries. We’ve been told this by the media and the government for years.

Saturated fat is the fat we store on our bodies, so if you eat it, surely it’s going to go straight on your hips and waist. Plus, if you put it down your sink, it’ll clog your pipes, so it must be the same in your arteries, right?

Well, perhaps things aren’t so straight forward as we’ve been told all these years.

More and more reputable scientific studies are refuting the links between saturated fats and heart disease, and the success of low carb diets have shown that it’s possible to burn fat while eating fat.

There is still far from a consensus however, and there are strong correlations between saturated fat consumption, obesity and heart disease.

This would definitely clog your sink. Better to eat it.stevepb / Pixabay

It’s so Good it’s Bad

Saturated Fat has two main characteristics.

  1. It’s High in Calories
  2. It’s Delicious

It’s my belief that this is the problem with saturated fat, and why on the one hand scientists find there to be nothing specifically dangerous related to its consumption, but at the same time that it is high correlated with obesity and lifestyle related illness.

The root cause of obesity, and the diseases of metabolic syndrome, is the over-consumption of calories.

As saturated fat is delicious and high in calories, it tends to facilitate this over-consumption.

Though, to be fair, few people actually gorge themselves on tubs of lard or sticks of butter.

I think it would be more accurate to say that obesity and heart disease are correlated with high calorie junk foods, which often contain saturated fat:

  • Pizzas
  • Burgers
  • Chips
  • Ice-Cream
  • Cakes
  • Biscuits
  • Pasties, etc, etc

People that reduce their saturated fat consumption, invariably cut out all these calorie dense, unsatiating foods, and replace them with lower calorie, nutrient dense, filling foods, thus reducing their calorie intake.

You’ll no doubt notice that this list is conspicuously similar to the lists of foods which people cut out on low-fat diets. This is no coincidence.

People talk about the “French Paradox” – that is that the French consume more saturated fat the US or the UK, yet have lower rates of obesity and heart disease (even with all that smoking!), but really there’s no paradox, they simply eat less junk and fewer calories.

How Much is Too Much?

There is nothing inherently bad about saturated fat. It is actually full of vitamins and other essential nutrients, especially when it comes from pasture raised meat, eggs or dairy.

Just as with carbs, however, you have to bear in mind that fat is energy, and if you eat more than you burn, it is destined to become body fat.

Also as with carbs, how much saturated fat is right for you is going to depend on you goals.

Fat Loss

If your goal is to shed body fat, it is probably best to stick to foods lower in fat, simply because these foods will be lower in calories, and therefore it will be easier to maintain a calorie deficit.

Just as it’s possible to do endurance training on a low carb diet, it’s possible to lose fat on a high fat diet. This doesn’t mean it’s the best or most sensible way to do it however.

In addition to cutting out processed junk foods and sticking to homemade meals made from wholefoods, consider the following changes:

  • Stick to lean meats/trim off the fat
  • Swap high fat cheeses for Cottage Cheese or Quark
  • Swap creamy or cheesy sauces for tomato based ones
  • Use as little fat in cooking as necessary
  • Steam, grill, slow-cook and stir fry.
  • Avoid deep-frying save for the very occasional treat!

I don’t recommend these changes because I think saturated fat is evil, or is going to kill you, only because all these changes will reduce the calorie content of your meals, without making them any less filling.


If you’re not looking to reduce body fat, there’s no reason to go out of your way to avoid saturated fat.

That said, it’s probably not advisable to go crazy either.

Though the French may be slimmer and healthier than Brits and Yanks, that doesn’t mean to say they’re all walking around with 6 packs until the age of 100. In fact, it’s not really all that to brag about when you think about it.

Fatty cuts of meat, cheese, and creamy sauces can all be enjoyed in moderation, providing they don’t become daily staples.

Eat mindfully and consider overall calorie content.


For most sports or activities, there’s no real benefit to increasing fat consumption.

Increasing carbs is the better method of increasing calorie content to fuel performance, as fat can’t replenish glycogen stores.

That said, the more active you are, the more calories you need, and fat can be a tasty source. Be aware though, that most people tend to over-estimate the calories burned from activity, so be careful not to go crazy!

One possible exception could be for long duration endurance sports.

Training after eating meals lower in carbs and higher in fat may help improve the bodies fat burning efficiency, and thereby improve endurance and performance.

Keep post workout meals high in carbs, and lower in fat though, to optimise muscle glycogen replenishment.


So, quite a hefty post in comparison to the previous weeks. Let me try to briefly summarise the Primal Guide to Fats:


Don’t eat these foods:

  • Trans=Fats/Hydrogenated Vegetable Oils
  • Industrially Produced Seed and Bean Oils
  • Foods Deep Fried in Vegetable Oils


Make these foods regular staples of your diet:

  • Oily Fish and Pastured Eggs
  • Olive Oil (Cold Pressed)
  • Unsalted Nuts and Seeds
  • Avocados


Consider your goals before eating the following foods. There’s no reason they shouldn’t form part of a healthy diet, but they are high in calories so don’t over do it:

  • Fatty Cuts of Meat
  • Fatty Cheeses
  • High Fat Sauces
  • Shallow Fried or Roasted Food
  • Anything else high in fat!

Hopefully this has given you a bit of food for thought, though it’s such a huge topic, it’s far from exhaustive.

If you have any specific questions, please post them below in the comments, and I’ll do my best to answer them!

Trans fats: chasing a global ban (BMJ) Rebecca Coombes

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