Good fats vs Bad fats [Data Analysis]

Today we want to analyse good fats vs bad fats to tell you exactly what you should eat and why.

Even more than cholesterol or other blood markers it appears clear that insulin resistance, elevated blood glucose and hyperinsulinemia increase your risk of heart disease, obesity, stroke, cancer andom dementia.[1]

An understanding of the food insulin index data tends to lead people to increase the fat content of their diet in in an effort to normalise blood glucose and reduce insulin levels.[2]


If a significant proportion of your calories are coming from fat it makes sense to look at the composition of our high fat food choices.

So let’s take a look what we could consider to be “good fats” and “bad fats” and the implications for prioritising our food choices.

Types of fats in food

You’re likely aware that there are different classifications of fat based on their chemical structure:

  • saturated,
  • monounsaturated, and
  • polyunsaturated.

What this means is that:

  • saturated fatty acids have no double bonds between individual carbon atoms (note: saturated fats are denoted by X:0 where the X is the length of the carbon chain and 0 is the number of double bonds),
  • monounsaturated fats have one double bond (e.g. X:1), and
  • polyunsaturated fats have more than one double bond (e.g. X:2).

If you want to learn more about this topic I suggest you check out this page on  It’s interesting to follow the links to see which foods are the highest in the different types of fats.

mainstream dietary advice on fat

The standard mainstream dietary advice is to to:

  1. avoid trans fats,
  2. limit saturated fats to less than 7% of energy intake,
  3. emphasise omega 3 fats, polyunsaturated fats and monounsaturated fats, and
  4. keep dietary fat to between 20 to 35% of energy intake.[3]

The Mediterranean Diet is typically promoted as being the ideal dietary model,[4] [5] [6] although interestingly in practice people from the Mediterranean region actually consume more than the recommended amount of fat, typically from olive oils and fatty fish.[7] [8] [9] [10]


food fat vs body fat

Jeff Volek and Steve Phinney in the Art and Science of Low Carbohydrate Performance[11] [12] note that the majority of human body fat consists of monounsaturated fatty acids, with smaller amounts of saturated fats and polyunsaturated fats.  They argue that if the body stores a greater proportion of monounsaturated fatty acids for energy in times of famine then it makes sense to align our dietary fat intake with these ratios.

The table below compares the composition of human adipose tissue[13] versus the proportion of fats across the 8000 foods in the USDA database.  Based on this logic it appears that we should go out of our way to emphasis monounsaturated fat given than saturated and polyunsaturated fats are plentiful in our food system.

% adipose


adipose / dietary













The chart below shows the relative proportions of each of the fatty acids in human adipose tissue.  Oleic acid (18:1) (a monounsaturated fat) is the most plentiful, followed by Palmitic acid (16:0) (a saturated fat) and Linoleic acid (18:2) (a polyunsaturated fat).image004

Taking Volek and Phinney’s logic a step further, the table below shows a comparison of the proportion of each fatty acid in our adipose tissue compared to their availability in the modern diet (based on the average across the 8000 foods in the USDA database).  It appears that we have more than enough Stearic acid (18:0), Linoleic acid (18:2) and Linolenic acid (18:3) available in the food system while a number of the other fatty acids are deficient.


adipose (mol %) % adipose dietary adipose / dietary class



3.0% 2.7% 110%




23.0% 17.4% 132%


16:1 n-7

7.2 7.7% 2.08% 369%



3.4 3.6% 9.2% 39%


18:1 n-9

43.5 46.5% 36.6% 127%


18:2 n-6

13.9 14.9% 17.5% 85%


18:3 n-3

0.8 0.9% 1.8% 48%


20:3 n-6

0.2 0.2% 0.012% 1744%


22:4 n-6

0.1 0.1% 0.004% 2426%


22:5 n-3

0.1 0.1% 0.1% 140%


22:6 n-3 0.1 0.1% 0.3% 37%


oleic acid vs linoleic acid

The two most prevalent fats in our diet and on our body are Oleic acid (18:1) and Linoleic acid (18:2).

While Linoleic acid (18:2) is considered to be an essential fatty acid [14] (meaning that the body cannot manufacture it from other dietary components) the data in the table above indicates that there is a relative abundance of it in the dietary system.

Many people believe that excess Linoleic acid (18:2) from vegetable oils (which causes an imbalance in our omega 3 : omega 6 ratio) is a major contributor to the obesity epidemic. [15]

The common wisdom is that olive oil, which is high in the monounsaturated fat Oleic acid (18:1), is a healthy ‘good fat’. [16]  When we look at the research it appears well established that emphasising the monounsaturated Oleic acid (18:1) and reducing the polyunsaturated Linoleic acid (18:2) will improved insulin resistance.[17] [18] [19] [20]

omega 3 fatty acids in foods

Improving the omega-3 : omega-6 ratio is widely regarded as important to reduce inflammation and optimise brain function and mental health.[21] [22]    Omega 3 fatty acids are typically obtained from seafood and are generally considered to be ‘good fats’ that we should be maximising for health.

While there appears to be plenty of DHA (22:6 n-3) available in the diet when we simply consider the composition of adipose tissue, it’s worth noting that DHA makes up 30% of the brain and 50% of our retina, so it is probably going to fall into the category of ‘good fats’ that we should be going out of our way to pursue in our diet.

A recent mouse study showed that fish oil (high in omega 3 fatty acids) is better than lard (high in saturated fatty acids, particularly palmitic acid (16:0) and stearic acid (18:0)) when it comes to weight gain, gut bacteria, obesity and insulin resistance.[23]  While people are clearly different from mice, it’s not unreasonable to think that fish oil might be better than eating lard.

Omega 3 fats are relatively rare in our food system which means we need to go out of our way to incorporate them into our diet.   The table below shows the omega 3 fatty acids that I think we should count as good fat along with the foods they are commonly found in.

isomer common name common foods
22:6 n-3 (DHA) Docosahexaenoic acid (DHA) fish oil, caviar, seal oil, cod liver oil, sardine oil
20:5 n-3 (EPA) Eicosapentaenoic acid (EPA) fish oil, caviar, fish
18:3 n-3 c,c,c (ALA) Alpha-linolenic acid peanut butter, flax seed, butter
22:5 n-3 (DPA) Docosapentaenoic acid (DPA) seal oil, fish oil – menhaden, fish oil – salmon.

MCT oil types

You might have heard a lot of talk about MCT (medium chain triglycerides) oils recently.  These shorter chain fats appear to bypass the lymphatic system and are transported directly to the liver via the portal vein.

Many people find benefit from using MCT oil as an aid to extend periods between meals or and cognitive enhancement.[24]  MCT oils are more readily turned into ketones which provide an alternative fuel source to the brain.   In turn, ketones can increase satiety[25] and decrease appetite, both of which may facilitate weight loss.[26]


MCTs make up about 1.1% of the fats in our food supply in coconut oil, butter, cheese and cream, however to get higher levels you will to supplement.

isomer common name common foods
12:0 Lauric acid palm kernel oil, coconut oil
10:0 Capric acid cheese, coconut oil, palm kernel oil
8:0 Caprylic acid coconut oil, coconut cream, palm kernel oil
6:0 Caproic acid butter, cheese, cream

trans fats in foods

Artificial trans fats (a.k.a. partially hydrogenated oils) are one of the few components of the diet that are widely accepted as unhealthy.[27]   If you look at the foods in which artificial trans fats are the most prevalent, it’s hard to disagree.

isomer common foods
18:1 t (g) soy shortening, margarine, canola oil
18:2 t (g) KFC, margarine
18:2 t,t (g) McDonald’s, fast foods
16:1 t (g) thickshake, cheeseburger, hamburger, fast foods

The issue with counting all trans fats as a bad fat is that they can also occur naturally in small amounts in meats and dairy such as grass fed beef.[28] [29]


Given that the USDA database does not differentiate between partially hydrogenated oils and naturally occurring trans fats, I have not assigned trans fats a negative mark.  Emphasising other ‘good fats’ will demote foods that contain artificial trans fats.

the effect of replacing carbohydrates with fat

The common view is that dietary fat, particularly saturated and trans fats, should be avoided in order to optimise blood cholesterol markers.  But what happens when we substitute fat for carbohydrates?

The chart below from a paper by cardiologist Dariush Mozaffarian[30] indicates that trans fats (TFA) have a negative impact on all blood markers (i.e. TC/HDL, LDL and HDL).  So there’s no disagreement there.

However increasing dietary saturated fat:

  • increases LDL (note: this is generally considered to be bad although it’s not clear if this is large buoyant of small dense LDL),
  • has minimal effect on the total cholesterol to HDL ratio, and
  • increases HDL (good).

Replacing carbohydrates (CHO) with either monounsaturated (MUFA) or polyunsaturated (PUFA) have what are generally regarded to be positive outcomes.


Whether or not saturated fat is beneficial starts to become a little clearer when we look at the effect of individual fatty acids.  The data below shows that while Lauric acid (12:0) increases LDL it also has very a positive effect on increasing HDL and decreasing the TC : HDL ratio.


saturated fats and insulin resistance

Mozaffarian says

“SFA has been considered a risk factor for insulin resistance and diabetes mellitus, but review of the current evidence indicates surprisingly equivocal findings. SFA consumption inconsistently affects insulin resistance in controlled trials and has not been associated with incident diabetes in prospective cohort studies.”[31]


Things start to get more interesting when you look at the relationship between individual fatty acids, insulin resistance and type 2 diabetes.

The investigators found that saturated fatty acids with an odd number of carbon atoms in their chain (15:0 and 17:0) were associated with a lower risk of type 2 diabetes, whereas even-chain saturated fatty acids””14:0, 16:0, and 18:0″”were associated with a higher risk.  Longer-chain saturated fatty acids (20:0, 22:0 and 24:0) also were found to be inversely associated with incident type 2 diabetes. [32] [33] [34]   

This also aligns with the mouse study that mentioned above where fish oil was found to have a better outcome on obesity and gut health compared to lard (which is high in 16:0 and 18:0).


The table below shows the foods that these ‘good fats’ are contained in.  Meat and nuts are embraced in the paleo and low carb scenes.  The benefits of dairy are debated, but this is typically related to the casein and lactose content which some people don’t tolerate well.

isomer common name common foods
17:0 Heptadecanoic acid tofu, lamb, beef
20:0 Arachidic acid macadamia nuts, peanut butter
22:0 Behenic acid peanut oil, peanut butter, sunflower oil, macadamia nuts
15:0 Pentadecanoic acid cream cheese, sour cream, lamb, beef
24:0 Lignoceric acid peanut butter, rosemary, macadamia nuts, cashew nuts, sunflower seeds


Listed below (in order of prevalence in the dietary system) are the ten fatty acids that I think should be included in the list of ‘good fats’ along with the common foods that they are contained in and the basis for their inclusion.

fatty acid common foods comment
Oleic acid (18:1) olive oil, sunflower oil, hazelnut oil, safflower oil, soybean oil, almond oil, avocado oil commonly associated with positive health outcomes and key component of Mediterranean diet

improves insulin resistance.

most abundant fatty acid in human adipose tissue

underrepresented in food system.

reduces TC:HDL ratio

Lauric acid (12:0) palm kernel oil, coconut oil increases HDL

decreases TC:HDL ratio.

Alpha-linolenic acid (18:3 n-3) peanut butter, flaxseed, nuts, cloves, cheese omega-3.

inflammation lowering

improves insulin resistance

Capric acid (10:0) cheese, coconut oil MCT oil.

Improves HDL:LDL ratio.

Docosahexaenoic acid (DHA) (22:6 n-3) fish oil – salmon, caviar, seal oil, cod liver oil, sardine oil essential fatty acid

omega 3.

abundant in human brain.

Arachidonic acid (20:4) salmon, chicken heart, liver, brain conditionally essential.

rare in food system.

Eicosapentaenoic acid (EPA) (20:5 n-3) fish oil, caviar, fish omega-3.

inflammation lowering.

improves brain function.

Margaric acid (17:0) tofu, lamb, frankfurter, beef sausage reduced risk of type 2 diabetes.
Docosapentaenoic acid (DPA) (22:5 n-3) seal oil, fish oil – menhaden, fish oil – salmon omega-3 though small quantities.
Pentadecanoic acid (15:0) cream cheese, sour cream, lamb. lower risk of type 2 diabetes

And for completeness listed below (in order of their prevalence in the dietary system) are the fatty acids in the USDA food database that didn’t make the ‘good fats’ list.

fatty acid common foods comment
Linoleic acid (18:2) safflower oil, grapeseed oil, sunflower oil, walnut oil n-6 component is essential however overly abundant in food system

substituting linoleic acid for oleic acid has been shown to improve insulin resistance

Palmitic acid (16:0) palm oil, fish oil – menhaden, butter, lard higher risk of type 2 diabetes

poor gut bacteria outcomes in mice study

Stearic acid (18:0) cocoa butter, shortening, margarine, lard increased risk of type 2 diabetes.

poor gut bacteria outcomes in mice study.

overly abundant in food system

18:1 c canola oil, margarine subset of 18:1 – no need to double count
18:2 n-6 c,c soy oil, sunflower oil, soybean oil, mayonnaise subset of 18:2.
Myristic acid (14:0) nutmeg, coconut oil Increased risk of type 2 diabetes
Palmitoleic acid (16:1) macadamia nuts, fish oil, seal, whale Increased risk of type 2 diabetes
Linolenic acid (18:3) flax seed, chia seed, walnuts, basil adequate in food system.

only count n-3 ALA component.

18:1 t Soy shortening, margarine, canola oil. trans fat
Gadoleic acid (20:0) seal, eel, fish oil – herring, fish –halibut, fish oil – cod liver, salmon small quantities and limited research.
Caprylic acid (8:0) coconut oil, coconut cream. MCT but rare in food system other than manufactured foods
Erucic acid (22:1) herring, halibut, sardine, cod liver no clear health benefits / research
Butyric acid (4:0) butter, cheese MCT but rare in food system other than manufactured foods
16:1 c KFC, Popeye’s, fast food predominantly in fast foods.
Caproic acid (6:0) butter, cheese, cream. MCT but rare in food system other than manufactured foods
Arachidic acid (20:0) macadamia nuts, peanut butter. reduced risk of type 2 diabetes but rare in food system.
Behenic acid (22:0) peanut oil, peanut butter, sunflower oil, macadamia  nuts, reduced risk of type 2 diabetes but rare in food system.
Myristoleic acid (14:0) frankfurter, beef sausage, bologna, cream cheese minimal research.

small quantities in food system

18:2 i soy oil, canola oil, margarine, French fries minimal research.

small quantities in food system

Heptadecenoic acid (17:0) tofu, broccoli, beef minimal research.

small quantities in food system

18:2 t KFC, margarine trans fat
18:4 fish oil – sardine, fish oil – salmon, fish oil – menhaden, oysters very small quantities in food system
Eicosadienoic acid (20:2 n-6 c,c) English muffin, margarine, fast foods, pine nuts, ham
Lignoceric acid (24:0) peanut butter, rosemary, macadamia nuts, cashew nuts, sunflower seeds reduced risk of type 2 diabetes
18:2 t,t MacDonald’s, fast foods trans fat
Eicosatrienoic acid (20:3) pine nuts, mustard, whitefish, seal, salmon appears beneficial but minimal quantities in food system
Pentadecenoic acid (15:0) tofu, miso, beef sausage appears beneficial but minimal quantities in food system
Gamma-linolenic acid (18:3 n-6) margarine omega 6

minimal quantities.

16:1 t thick shake, cheeseburger, hamburger, fast foods. trans fat
20:3 n-6 KFC, Popeye’s, fast food. Omega 6 and primarily in fast food
Nervonic acid (24:1 c) mustard, salmon, seal, flax seed likely beneficial, but minimal quantities
22:1 c margarine. minimal quantities in food system

good fat foods

Shown below is the list of fatty foods sorted by their relative quantity of the good fats with their percentage of insulinogenic calories also shown.  The order itself is not that important (otherwise the seals and whales would be even more endangered due to this article), however the big winners are:

  • fish oil (seal, whale, menhaden, sardine, herring, salmon, cod liver),
  • fish (smelt, salmon, herring, caviar, mackerel, caviar, trout, swordfish),
  • lamb, pork and beef, and
  • cheese, butter and cream.
food % insulinogenic nutrient density
oil – bearded seal 0% 20.6
oil – beluga whale 0% 17.9
oil – spotted seal 0% 17.4
smelt – dried 33% 14.4
salmon 39% 14.1
fish oil – cod liver 0% 14.0
fish oil – salmon 0% 13.4
fish oil – sardine 0% 13.1
fish oil – menhaden 0% 13.0
fish oil – herring 0% 12.7
lamb fat 2% 12.7
mackerel 14% 11.5
pork fat 3% 11.0
whitefish 38% 10.9
cream cheese 8% 10.4
caviar 26% 10.3
bacon fat 0% 9.8
butter 0% 9.0
roe 37% 8.9
sablefish 16% 8.7
seal 22% 8.5
beef steak 21% 8.3
parmesan cheese 24% 8.2
herring 19% 8.2
whitefish 33% 8.2
pepperoni 10% 8.1
beef sausage 9% 7.5
turkey fat 0% 7.1
lamb 16% 7.1
macadamia nuts 5% 7.0

It’s important to keep in mind that consuming enough “good fats” is only part of the nutrition story.  In the next article we’ll look at how we can use this understanding of good fats along with our understanding of vitamins, mineral and amino acids to identify the most nutrient dense foods for different goals.




































11 thoughts on “Good fats vs Bad fats [Data Analysis]”

  1. Once again, as always, thank you for your ambitious work!
    Since 2008 I ordered cream with my coffee, from 2015 I do it because I am on a LCHF diet (70%+ fat). One day while having this perfect cream on my coffee in a restaurant I realized that it was not cream on my coffee but some other synthetic concoction. I bribed the waitress to bring me the “box”.
    The cream about all the restaurants use in South Africa is mostly imported from China and have lovely brand names like Millac: high whip volume & excellent stability (will you believe); Versatié: the cooking, pouring whipping solution and Meadowland: Delight and more.
    Not only are these concoction (margarine undercover) served with coffee, but they bake with it and they make our creamed spinach with it and the lovely creamed mushroom sauce and….
    Many canned tuna brands we get in South Africa is about always without fat, yes zero “0” fat, which include big brand names like King Oscar that goes so far as to sell tinned sardines with zero oil.
    There is also something I must work out, every time I eat white fish in a restaurant I wake up 2-3 in the morning flushing, sweating with heart palpitations (histamine/MSG/insulin reaction?). It feels like a menopausal flush, but consistently after a white fish meal and also some other restaurant meals-I am sure there are women on HRT treatment because of these symptoms. Eating white fish, from frozen, at home is not a problem.
    MSG is the standard in all our salt in restaurants. When was the last time you saw rice in a salt pot? MSG is not hygroscopic, it keeps the restaurant salt dry.
    We must realise that restaurants use restaurant-grade-everything. From the 5 gallon salad sauces and mayonnaise to the oils they use for grilling steak, yes, everything. Low quality oil decanted into cold pressed virgin olive oil bottles on the restaurant tables to impress customers.
    When on a LCHF diet it is important to choose the correct food from a menu or know the restaurateur and the ingredients they use. I was even served plastic cream on my coffee at a restaurant on a farm that makes cheese for a living. Do they use this in their cheese making? Does it ferment? Who will know? Does it make sense? Google….

    O my word, yes they do:
    Imagine a caprese salad with synthetic/margerine mozarella.

    Maybe we must begin by standing up for ourselves and launch a war on the food/restaurant industry! Am I a neurotic consumer?
    Back to the drawing board Marty-you have not given us the breakdown of these alien substances.
    Gosh. The LCHF way of eating may be the deadliest diet on the planet! in our modern society.

    • Sandra, wholy moly, you have definitely given me food for thought. In Holland (where I live) MSG is added to EVERYTHING including prawns, sold as fresh North Sea prawns. I know they get sent to Morocco to get shelled, where I am sure they add the MSG in order to preserve them. .
      On the pizzas you buy in the supermarket the cheese on the top is not genuine, but fake cheese. It was dealt with on a TV program called “Keuringsdienst van waarde” (inspection service of value rough translation) and I’m sure pizzarias and McDonalds also use the fake cheese.
      If you are a neurotic consumer, than I am as well and millions of other critical consumers who don’t want trash in their bodies with us.

      • Here in America, the “meat” on frozen pizzas isn’t even meat–it’s SOY, which is not good for diabetics, as it is a known hormone disruptor. So who’s fault is this? Not the food manufacturers, but Congress!

        It’s a Matrix world we live in these days as far as food goes. Nothing is as it seems.

    • Matrix food–canned fish packed in “oil” isn’t even packed in a good oil. They use soy oil, because it’s cheaper. Now do you REALLY want canned fish packed in oil?

      Even the stuff labeled as “packed in olive oil” isn’t really packed in olive oil, since most of the olive oil floating around out there is really soy oil with just a splash of olive oil in it for color and flavor.

      You want REAL olive oil? Gotta go to Italy–olive oil cartels are hoarding the good stuff, and selling doctored soy oil worldwide.

      • Wenchypoo, I agree with you that the stuff we buy in supermarkets isn’t the genuine article. Not for 3 euro’s a bottle!! I buy my olive oil at a farmer’s market who has an olive grove in Spain and sells it privately for 15 euros a liter. It tastes like the genuine stuff, so I have to take him on trust. I’ve been told that to tell if it’s genuine olive oil is to put the bottle in the fridge and if it gets cloudy, then you’ve got the good stuff. Mine definitely does.

  2. Hi, This is something really new – sunflower oil rich in Oleic acid (18:1) and canola in trans fat. Could you share where did you find that. I would like to learn more.

Comments are closed.