Does Eating Fat Make You Fat? The Surprising Truth About Cholesterol and Saturated fat!

“Good fats vs “bad fats”?

Which ones do you need more of?

Which ones will drive you to eat more and just end up on your belly and bum?

Our data analysis of forty thousand days of food logging from more than a thousand optimisers found that we have a strong craving for cholesterol and omega 3, which we struggle to get enough of these in our modern diet. Once we get enough of these fats, we tend to eat less.

However, foods that contain more polyunsaturated and monounsaturated fats (which are more prevalent in modern seed oils) will just cause you to eat more!

Meanwhile, our satiety response to saturated fat might surprise you!

In the last article, we looked at the effect of macronutrients (i.e. protein, fat, carbohydrates, fibre and alcohol) on satiety to help us understand how our food choices can help us control our appetite.   

In this article, we’ll drill down into the following fatty acids to understand which ones align with satiety and the ones that will increase your likelihood to overeat:

  • omega 3
  • omega 6, 
  • cholesterol,
  • trans fats, 
  • saturated fat, 
  • monounsaturated fat, and 
  • polyunsaturated fats.  


This is the third of an eight-part series on the effect of macro and micronutrients on satiety.

While we usually think about fat as a single macronutrient, there are several fatty acids that generate different responses in our body.  Making an informed choice about your fat intake and the foods that contain them is crucial to optimise your health and tame your appetite.  

Does eating fat make you fat?

The chart below shows our satiety response to the percentage of fat in our diet. As a general rule, we tend to consume more energy when we eat more fat. 

However, each of the fractions of fat causes a different response in your body. Some fats are essential and need to be consumed regularly in the food you eat.  Hence, they satisfy our cravings and help you eat less when we get enough of them.

Good fats vs bad fats

Some people prefer unsaturated fats (that come mainly from plants) and shun animal-based saturated fat while others prefer saturated fat and avoid seed oils.  However, nearly all foods contain a mixture of different types of fats. So, it’s impossible to completely avid one type of fat.

The table below shows the breakdown of the intake of the various fat sources consumed by Optimisers.  On average, Optimisers get 52% of their energy from fat. Saturated fat is the largest source of energy, followed by monounsaturated and polyunsaturated. Meanwhile, omega 3, transfat and cholesterol only contribute a small proportion of energy in our diet.  

fataverage (g)%
unsaturated fats48.922%
omega 32.91.3%
trans fat1.00.4%
total fat11552%

Omega 3 

Omega 3 is an essential fat that we can’t make, so we need to get it from the food we eat. 

Given that it is essential, it makes sense that our body would have an increased appetite for omega 3 fatty acids.  This means we eat more food until we get enough. Once we get enough omega 3, our appetite for these foods subsides.

Just like we get bored eating the same food again and again or we get full when we’ve had a big meal, once we get enough of a nutrient, we lose interest in the food that contains it and go in search of other nutrients.  

The chart below shows the satiety response to omega 3 fatty acids. Once we get an omega 3 intake of more than 3 g/2000 calories, we see an improved satiety response.  

But our satiety response to foods that contain more omega 3 fatty acids starts to taper off beyond 7 g/2000 calories. So there’s not much use pushing your omega 3 intake any higher with supplements.

The omega 3 frequency distribution chart below shows that a stretch target of 6 g/2000 calories is achievable with whole foods (but not necessarily easy to do).  Most people aren’t eating that much seafood (which tends to contain plenty of protein and lots of other beneficial nutrients).

While plant-based foods contain some omega 3 as alpha-linolenic acid (ALA), humans are not good at converting it to the bioactive forms (i.e. DHA and EPA).  Consuming fatty fish and other seafood gives us a better chance of absorbing it.  

The most plentiful and bioavailable source of omega 3 is fatty fish (e.g. salmon, mackerel, sardines, halibut, arctic char, lingcod and caviar).  Popular Omega 3 sources are shown in the table below.  

food Omega 3
mussels 5%
tuna 2%

Before you reach for the supplement bottle, keep in mind that, while omega 3 is essential, you’re unlikely to get all the satiety and health benefits from supplements.  Foods that are high in omega 3 provide many other beneficial nutrients, so you should do everything you can to meet your omega 3 target from the food you eat.

Omega 6 

While some omega 6 is essential, as we get more of our energy from omega 6, we tend to eat more total calories. 

Omega 6 fatty intake leads to hyperactivity of the endocannabinoid system, which is an important regulator of appetite. A high intake of omega 6 fats effectively leads us to an addition to the foods that contain a lot of them.   

While we need some omega 6 fats in our diet (because they are essential), most people are getting way more than they need from the seed oils that are added as ingredients to many of our processed foods.  

Omega 3 and omega 6 fatty acids compete for the same conversion enzymes.  Excessive omega 6 causes inflammation and overwhelm the anti-inflammatory properties of omega 3 in your body.  

A diet with a high amount of omega 6 and relatively small amounts of omega 3 will increase inflammation. Conversely, a diet containing a lot of omega 3 and not too much omega 6 will reduce inflammation.

Omega 6:omega 3 ratio

Beyond the absolute value of omega 3 or omega 6, your ratio of omega 6:omega 3 ratio is even more critical.  


The chart below shows the satiety response to the omega 6:3 ratio from Optimiser data.  To the left of this chart, we can see that we get a strong satiety response when we have an omega 6:3 ratio of less than 2.   

The frequency distribution chart shows that an optimal ratio (i.e. less than 1) is possible, but not common.  Even in this population of people focusing on nutrient density, there is a significant number of people with an omega 6:3 ratio of greater than 10 (which is not ideal).

The key to improving your omega 6:omega 3 ratio is to prioritise seafood and avoid processed foods that contain some form of seed oil as an ingredient.


Cholesterol is a controversial nutrient with a chequered history. 

The reality is, we need cholesterol to build our cell membranes, make hormones and produce bile acids.

It has been thought that dietary cholesterol contributes to cholesterol in the blood, which was associated with heart disease.  On this basis, the American Heart Association set a limit on cholesterol of 300 mg per day, and since the 1950s, the US population dutifully reduced their intake of dietary cholesterol.  

However, the 2015 Dietary Guidelines quietly removed cholesterol as a ‘nutrient of concern’ due to the lack of evidence that it is harmful.  It turns out that your liver regulates the cholesterol in your blood, and the levels are not strongly correlated with dietary intake.  

The best thing you can do to achieve healthy blood cholesterol levels is to focus on improving satiety to avoid energy toxicity, which will lead to healthy levels of body fat along with healthy blood sugar and fat in your blood.

Our satiety analysis suggests that foods that contain more cholesterol lead to greater satiety.  Your body craves cholesterol and continues to seek out cholesterol-containing foods until it gets enough.  As shown in the chart below, increasing your cholesterol intake from 0.3 to 0.9 g per 2000 calories corresponds with a 7% reduction in energy intake.

Concerningly, the lower limit targeted by the American Heart Association and the Dietary Guidelines aligns with the lowest satiety response!  Unfortunately, lower satiety due to cholesterol avoidance will drive overeating, obesity and eventually heart disease.

Popular foods that contain more cholesterol are listed below.  These are generally nutritious foods and should not be avoided due to fear of their high cholesterol content.  

food % cholesterol
egg yolk3.0%
liver 3.0%
whole egg2.3%
fish oil0.5%
pork  0.4%

As with omega 3, it’s unlikely that you’ll benefit as much if you only focus on increasing your cholesterol in the absence of whole food.  There’s no need to go out of your way to drink butter or coconut oil which are not particularly nutrient-dense. However, there is no need to avoid foods like eggs, liver and seafood contain cholesterol in a matrix of many other beneficial nutrients.

Trans Fats 

Trans fats are another controversial fat (even more than cholesterol).  

Image result for trans fats

The mainstream recommendation is to limit trans fats to less than 1% of your energy intake.  This limit is higher than the general population average intake of trans fats of 0.6% and the Optimiser average of 0.5%.

It’s important to make the distinction between naturally occurring trans fats and those that are industrially produced.  While harmless naturally-occurring trans fats are present in dairy and animal products, dangerous industrial trans fats are created by pumping hydrogen molecules into liquid vegetable oil, changing the chemical structure and causing the oil to become solid.

Industrial trans fats are high in partially hydrogenated vegetable fats (e.g. deep-fried foods and baked foods like biscuits, cakes, pastries and buns).  But if you are minimising processed foods, you will be keeping your intake of industrially-produced trans fats to a minimum anyway.  

While there is no reason to prioritise trans fats, it doesn’t make a big difference in terms of satiety compared to the parameters discussed in this series.  If you are avoiding deep-fried and highly processed foods while focusing on nutrient-dense foods, naturally occurring trans fats should not be a concern.  

Foods that contain dangerous trans fats that should be avoided include shortening, margarine, soy oil, canola oil, and pastries. 

Popular foods that contain more naturally occurring trans fats (that you don’t need to be concerned about) include ground beef (4%), butter (3%), Parmesan cheese (2%), and liver (1%).  

Monounsaturated fat 

Our consumption of monounsaturated fat has been on the rise since we discovered how to extract oil from plants using chemical solvents in 1907.  Since then, these unsaturated fats (from soy, rapeseed/canola and corn) have grown to dominate our food supply.  

The chart below shows that we tend to consume about 25% more energy when our diet contains more monounsaturated fat. 

If you want to lose body fat, you should ideally consume no more than 7% of your energy from monounsaturated fat.  

Popular foods that contain more monounsaturated fats include:

  • olive oil (74%), 
  • avocado oil (72%), 
  • avocados (55%), 
  • pecans (53%), 
  • almonds (49%), 
  • lard (45%), 
  • cashews (40%), 
  • peanuts (39%), and 
  • bacon (38%).  

Polyunsaturated fat 

Although it makes up a smaller portion of our energy intake than monounsaturated fats, our consumption of polyunsaturated fats has followed a similar trajectory over the last century.

We tend to eat more when we consume more polyunsaturated fat.  If you want to improve satiety and reduce your energy intake, it makes sense to set a stretch target of no more than 3% of your calories from polyunsaturated fats.  

Popular foods that contain more polyunsaturated fat include:

  • walnuts (65%), 
  • mayonnaise (59%), 
  • flaxseeds (48%), 
  • brazil nuts (33%), 
  • pecans (28%), and 
  • peanuts (33%).  

Unsaturated fats 

Looking at polyunsaturated and monounsaturated together (i.e. unsaturated fats), we see that we tend to consume around 15% more calories when our unsaturated fats (i.e. poly and mono) increase above about 25% of our total energy intake. 

If you want to lose weight, a reasonable stretch target would be less than 17% of your energy from unsaturated (i.e. fats from refined vegetable oils).

Popular foods that contain more polyunsaturated fats include:

  • avocado oil (86%), 
  • olive oil (85%), 
  • mayonnaise (81%), 
  • pecans (81%), and 
  • walnuts (77%).  

While many of these foods are healthy in moderation, you really want to avoid processed foods that contain unsaturated fats as ingredients (e.g. sunflower, canola, soy or safflower oils)

Saturated fat 

The data from the USDA Economic Research Service indicates that our intake of saturated fat has increased over the last century (see the red line in the chart below). However, the monounsaturated and polyunsaturated fats in our diet have increased much more.  

In percentage terms, saturated fat has decreased from about 42% of calories to less than 32% of calories since the 1930s.

Over the past half-century, our intake of foods that contain more saturated fat (e.g. dairy, butter and lard) have not changed significantly, while our use of unsaturated “salad and cooking oils” (i.e. mainly extracted from soy, canola and corn and used as an ingredient in our food) have skyrocketed!   

The satiety response chart shown below indicates that we eat more calories when we consume more saturated fat, but only up until about 30% of calories.   Beyond around 35%, we tend to get an improved satiety response to saturated fats.  This may be because processed foods that contain saturated fat as an ingredient along with other types of fat are less satiating than whole foods that contain a larger proportion of their energy as saturated fat.

Examples of popular foods that contain more saturated fat include:

  • coconut oil (83%), 
  • butter (57%), 
  • lard (47%), 
  • Parmesan cheese (33%), 
  • bacon (33%), 
  • ground beef (27%), 
  • Brazil nuts (22%), and 
  • eggs (20%).  

While you probably don’t need to prioritise saturated fats by going out of your way to add butter and coconut oil to everything (especially if your goal is weight loss), this data indicates that there is no need to actively avoid nutritious foods that contain saturated fat (e.g. eggs, cheese and meat).  

Comparison chart

To bring all this together, the chart below shows the satiety response curves for the different types of fat plotted on the one chart.  

  • Foods that contain more omega 3 and cholesterol tend to be more satiating.  Avoidance of foods that are otherwise nutritious and contain energy as cholesterol or omega 3 tends to have a negative impact on satiety.  
  • Monounsaturated and saturated fats, polyunsaturated fats also have a negative impact on satiety.  

The chart below shows the two most significant sources of fat, saturated fat and monounsaturated fat on the same chart.  While increasing calories from either saturated fat or monounsaturated do not promote satiety, the data indicate that higher intakes of monounsaturated fat have more of a detrimental effect on satiety compared to saturated fat at higher levels.  

Saturated fat as part of an otherwise nutritious part of whole food should not be actively avoided.  However, your intake of monounsaturated fats (that tend to be plentiful as an ingredient in processed foods from refined seed oils) should be actively managed if you want to control your appetite. 


The table below summarises the various fatty acid parameters in terms of:

  • average Optimiser intake,
  • stretch target (i.e. to improve satiety and maximise weight loss),
  • the population average intake (based on data from the USDA Economic Research Service), and 
  • the stretch target as a percentage of the population average.  
nutrient Optimiser averagestretch target population average
fat (%)52%< 34%42%
cholesterol (g)0.7NA0.2
omega 6:3 ratio7.8< 2no data 
monounsaturated (%)16%< 7%17%
saturated fat (%) 19%< 13%13%
unsaturated fat (%)22%17%26%
omega 3 (g)2.9> 6.0no data 
polyunsaturated (%)6%< 3%10%
omega 6 (%)5.3%< 3.0%no data 
trans fat0.4%< 1%no data 

This next show the targets for men (2000 cals) and women (1600 calls) that you could use in Cronometer if you wanted to actively manage your fat intake to maximise satiety.

nutrient stretch (men)stretch (women)
monounsaturated < 16 g< 12g
polyunsaturated< 7.0 g< 5.5 g
poly + mono< 38 g< 30 g
fat < 76 g< 60 g
omega 3 > 6.0 g> 4.8 g
omega 6< 7.6 g< 6.0 g
trans fat < 2.2 g< 1.8 g
saturated < 30 g< 24 g

In practice, this would look involve:

  • reducing your intake of foods that are contributing the most to your monounsaturated fat intake, 
  • increasing your intake of foods that contain more omega 3 fatty acids, and 
  • pursuing nutrient-dense foods without any concern for cholesterol.

Where do I start?

After four years of digging into the theory, we’ve created some exciting tools to help you optimise your nutrition:

To help you understand what nutrients you need to focus on (and which foods and meals contain them) we have created a simple free 7 Day Food Discovery Challenge.

Up next…

In our next article in this series, we’ll be looking at the satiety response to minerals.